We get a bug during ltp can_filter test as following.
===========================================
[60919.264984] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
[60919.265223] PGD 8000003dda726067 P4D 8000003dda726067 PUD 3dda727067 PMD 0
[60919.265443] Oops: 0000 [#1] SMP PTI
[60919.265550] CPU: 30 PID: 3638365 Comm: can_filter Kdump: loaded Tainted: G W 4.19.90+ #1
[60919.266068] RIP: 0010:selinux_socket_sock_rcv_skb+0x3e/0x200
[60919.293289] RSP: 0018:ffff8d53bfc03cf8 EFLAGS: 00010246
[60919.307140] RAX: 0000000000000000 RBX: 000000000000001d RCX: 0000000000000007
[60919.320756] RDX: 0000000000000001 RSI: ffff8d5104a8ed00 RDI: ffff8d53bfc03d30
[60919.334319] RBP: ffff8d9338056800 R08: ffff8d53bfc29d80 R09: 0000000000000001
[60919.347969] R10: ffff8d53bfc03ec0 R11: ffffb8526ef47c98 R12: ffff8d53bfc03d30
[60919.350320] perf: interrupt took too long (3063 > 2500), lowering kernel.perf_event_max_sample_rate to 65000
[60919.361148] R13: 0000000000000001 R14: ffff8d53bcf90000 R15: 0000000000000000
[60919.361151] FS: 00007fb78b6b3600(0000) GS:ffff8d53bfc00000(0000) knlGS:0000000000000000
[60919.400812] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[60919.413730] CR2: 0000000000000010 CR3: 0000003e3f784006 CR4: 00000000007606e0
[60919.426479] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[60919.439339] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[60919.451608] PKRU: 55555554
[60919.463622] Call Trace:
[60919.475617] <IRQ>
[60919.487122] ? update_load_avg+0x89/0x5d0
[60919.498478] ? update_load_avg+0x89/0x5d0
[60919.509822] ? account_entity_enqueue+0xc5/0xf0
[60919.520709] security_sock_rcv_skb+0x2a/0x40
[60919.531413] sk_filter_trim_cap+0x47/0x1b0
[60919.542178] ? kmem_cache_alloc+0x38/0x1b0
[60919.552444] sock_queue_rcv_skb+0x17/0x30
[60919.562477] raw_rcv+0x110/0x190 [can_raw]
[60919.572539] can_rcv_filter+0xbc/0x1b0 [can]
[60919.582173] can_receive+0x6b/0xb0 [can]
[60919.591595] can_rcv+0x31/0x70 [can]
[60919.600783] __netif_receive_skb_one_core+0x5a/0x80
[60919.609864] process_backlog+0x9b/0x150
[60919.618691] net_rx_action+0x156/0x400
[60919.627310] ? sched_clock_cpu+0xc/0xa0
[60919.635714] __do_softirq+0xe8/0x2e9
[60919.644161] do_softirq_own_stack+0x2a/0x40
[60919.652154] </IRQ>
[60919.659899] do_softirq.part.17+0x4f/0x60
[60919.667475] __local_bh_enable_ip+0x60/0x70
[60919.675089] __dev_queue_xmit+0x539/0x920
[60919.682267] ? finish_wait+0x80/0x80
[60919.689218] ? finish_wait+0x80/0x80
[60919.695886] ? sock_alloc_send_pskb+0x211/0x230
[60919.702395] ? can_send+0xe5/0x1f0 [can]
[60919.708882] can_send+0xe5/0x1f0 [can]
[60919.715037] raw_sendmsg+0x16d/0x268 [can_raw]
It's because raw_setsockopt() concurrently with
unregister_netdevice_many(). Concurrent scenario as following.
cpu0 cpu1
raw_bind
raw_setsockopt unregister_netdevice_many
unlist_netdevice
dev_get_by_index raw_notifier
raw_enable_filters ......
can_rx_register
can_rcv_list_find(..., net->can.rx_alldev_list)
......
sock_close
raw_release(sock_a)
......
can_receive
can_rcv_filter(net->can.rx_alldev_list, ...)
raw_rcv(skb, sock_a)
BUG
After unlist_netdevice(), dev_get_by_index() return NULL in
raw_setsockopt(). Function raw_enable_filters() will add sock
and can_filter to net->can.rx_alldev_list. Then the sock is closed.
Followed by, we sock_sendmsg() to a new vcan device use the same
can_filter. Protocol stack match the old receiver whose sock has
been released on net->can.rx_alldev_list in can_rcv_filter().
Function raw_rcv() uses the freed sock. UAF BUG is triggered.
We can find that the key issue is that net_device has not been
protected in raw_setsockopt(). Use rtnl_lock to protect net_device
in raw_setsockopt().
Fixes: c18ce101f2e4 ("[CAN]: Add raw protocol")
Signed-off-by: Ziyang Xuan <[email protected]>
---
net/can/raw.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/can/raw.c b/net/can/raw.c
index ed4fcb7ab0c3..a63e9915c66a 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -546,6 +546,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
return -EFAULT;
}
+ rtnl_lock();
lock_sock(sk);
if (ro->bound && ro->ifindex)
@@ -588,6 +589,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
dev_put(dev);
release_sock(sk);
+ rtnl_unlock();
break;
@@ -600,6 +602,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
err_mask &= CAN_ERR_MASK;
+ rtnl_lock();
lock_sock(sk);
if (ro->bound && ro->ifindex)
@@ -627,6 +630,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
dev_put(dev);
release_sock(sk);
+ rtnl_unlock();
break;
--
2.25.1
On Wed, Jul 21, 2021 at 09:09:37AM +0800, Ziyang Xuan wrote:
> We get a bug during ltp can_filter test as following.
>
> ===========================================
> [60919.264984] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> [60919.265223] PGD 8000003dda726067 P4D 8000003dda726067 PUD 3dda727067 PMD 0
> [60919.265443] Oops: 0000 [#1] SMP PTI
> [60919.265550] CPU: 30 PID: 3638365 Comm: can_filter Kdump: loaded Tainted: G W 4.19.90+ #1
> [60919.266068] RIP: 0010:selinux_socket_sock_rcv_skb+0x3e/0x200
> [60919.293289] RSP: 0018:ffff8d53bfc03cf8 EFLAGS: 00010246
> [60919.307140] RAX: 0000000000000000 RBX: 000000000000001d RCX: 0000000000000007
> [60919.320756] RDX: 0000000000000001 RSI: ffff8d5104a8ed00 RDI: ffff8d53bfc03d30
> [60919.334319] RBP: ffff8d9338056800 R08: ffff8d53bfc29d80 R09: 0000000000000001
> [60919.347969] R10: ffff8d53bfc03ec0 R11: ffffb8526ef47c98 R12: ffff8d53bfc03d30
> [60919.350320] perf: interrupt took too long (3063 > 2500), lowering kernel.perf_event_max_sample_rate to 65000
> [60919.361148] R13: 0000000000000001 R14: ffff8d53bcf90000 R15: 0000000000000000
> [60919.361151] FS: 00007fb78b6b3600(0000) GS:ffff8d53bfc00000(0000) knlGS:0000000000000000
> [60919.400812] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [60919.413730] CR2: 0000000000000010 CR3: 0000003e3f784006 CR4: 00000000007606e0
> [60919.426479] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [60919.439339] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [60919.451608] PKRU: 55555554
> [60919.463622] Call Trace:
> [60919.475617] <IRQ>
> [60919.487122] ? update_load_avg+0x89/0x5d0
> [60919.498478] ? update_load_avg+0x89/0x5d0
> [60919.509822] ? account_entity_enqueue+0xc5/0xf0
> [60919.520709] security_sock_rcv_skb+0x2a/0x40
> [60919.531413] sk_filter_trim_cap+0x47/0x1b0
> [60919.542178] ? kmem_cache_alloc+0x38/0x1b0
> [60919.552444] sock_queue_rcv_skb+0x17/0x30
> [60919.562477] raw_rcv+0x110/0x190 [can_raw]
> [60919.572539] can_rcv_filter+0xbc/0x1b0 [can]
> [60919.582173] can_receive+0x6b/0xb0 [can]
> [60919.591595] can_rcv+0x31/0x70 [can]
> [60919.600783] __netif_receive_skb_one_core+0x5a/0x80
> [60919.609864] process_backlog+0x9b/0x150
> [60919.618691] net_rx_action+0x156/0x400
> [60919.627310] ? sched_clock_cpu+0xc/0xa0
> [60919.635714] __do_softirq+0xe8/0x2e9
> [60919.644161] do_softirq_own_stack+0x2a/0x40
> [60919.652154] </IRQ>
> [60919.659899] do_softirq.part.17+0x4f/0x60
> [60919.667475] __local_bh_enable_ip+0x60/0x70
> [60919.675089] __dev_queue_xmit+0x539/0x920
> [60919.682267] ? finish_wait+0x80/0x80
> [60919.689218] ? finish_wait+0x80/0x80
> [60919.695886] ? sock_alloc_send_pskb+0x211/0x230
> [60919.702395] ? can_send+0xe5/0x1f0 [can]
> [60919.708882] can_send+0xe5/0x1f0 [can]
> [60919.715037] raw_sendmsg+0x16d/0x268 [can_raw]
>
> It's because raw_setsockopt() concurrently with
> unregister_netdevice_many(). Concurrent scenario as following.
>
> cpu0 cpu1
> raw_bind
> raw_setsockopt unregister_netdevice_many
> unlist_netdevice
> dev_get_by_index raw_notifier
> raw_enable_filters ......
> can_rx_register
> can_rcv_list_find(..., net->can.rx_alldev_list)
>
> ......
>
> sock_close
> raw_release(sock_a)
>
> ......
>
> can_receive
> can_rcv_filter(net->can.rx_alldev_list, ...)
> raw_rcv(skb, sock_a)
> BUG
>
> After unlist_netdevice(), dev_get_by_index() return NULL in
> raw_setsockopt(). Function raw_enable_filters() will add sock
> and can_filter to net->can.rx_alldev_list. Then the sock is closed.
> Followed by, we sock_sendmsg() to a new vcan device use the same
> can_filter. Protocol stack match the old receiver whose sock has
> been released on net->can.rx_alldev_list in can_rcv_filter().
> Function raw_rcv() uses the freed sock. UAF BUG is triggered.
>
> We can find that the key issue is that net_device has not been
> protected in raw_setsockopt(). Use rtnl_lock to protect net_device
> in raw_setsockopt().
>
> Fixes: c18ce101f2e4 ("[CAN]: Add raw protocol")
> Signed-off-by: Ziyang Xuan <[email protected]>
> ---
> net/can/raw.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/net/can/raw.c b/net/can/raw.c
> index ed4fcb7ab0c3..a63e9915c66a 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -546,6 +546,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> return -EFAULT;
> }
>
> + rtnl_lock();
> lock_sock(sk);
>
> if (ro->bound && ro->ifindex)
> @@ -588,6 +589,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> dev_put(dev);
>
> release_sock(sk);
> + rtnl_unlock();
>
> break;
>
> @@ -600,6 +602,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>
> err_mask &= CAN_ERR_MASK;
>
> + rtnl_lock();
> lock_sock(sk);
>
> if (ro->bound && ro->ifindex)
> @@ -627,6 +630,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> dev_put(dev);
>
> release_sock(sk);
> + rtnl_unlock();
>
> break;
>
> --
> 2.25.1
>
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
On 21.07.21 06:53, Greg KH wrote:
> On Wed, Jul 21, 2021 at 09:09:37AM +0800, Ziyang Xuan wrote:
>> We get a bug during ltp can_filter test as following.
>>
>> ===========================================
>> [60919.264984] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
>> [60919.265223] PGD 8000003dda726067 P4D 8000003dda726067 PUD 3dda727067 PMD 0
>> [60919.265443] Oops: 0000 [#1] SMP PTI
>> [60919.265550] CPU: 30 PID: 3638365 Comm: can_filter Kdump: loaded Tainted: G W 4.19.90+ #1
This kernel version 4.19.90 is definitely outdated.
Can you please check your issue with the latest uptream kernel as this
problem should have been fixed with this patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d0caedb759683041d9db82069937525999ada53
("can: bcm/raw/isotp: use per module netdevice notifier")
Thanks!
>> [60919.266068] RIP: 0010:selinux_socket_sock_rcv_skb+0x3e/0x200
>> [60919.293289] RSP: 0018:ffff8d53bfc03cf8 EFLAGS: 00010246
>> [60919.307140] RAX: 0000000000000000 RBX: 000000000000001d RCX: 0000000000000007
>> [60919.320756] RDX: 0000000000000001 RSI: ffff8d5104a8ed00 RDI: ffff8d53bfc03d30
>> [60919.334319] RBP: ffff8d9338056800 R08: ffff8d53bfc29d80 R09: 0000000000000001
>> [60919.347969] R10: ffff8d53bfc03ec0 R11: ffffb8526ef47c98 R12: ffff8d53bfc03d30
>> [60919.350320] perf: interrupt took too long (3063 > 2500), lowering kernel.perf_event_max_sample_rate to 65000
>> [60919.361148] R13: 0000000000000001 R14: ffff8d53bcf90000 R15: 0000000000000000
>> [60919.361151] FS: 00007fb78b6b3600(0000) GS:ffff8d53bfc00000(0000) knlGS:0000000000000000
>> [60919.400812] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [60919.413730] CR2: 0000000000000010 CR3: 0000003e3f784006 CR4: 00000000007606e0
>> [60919.426479] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> [60919.439339] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> [60919.451608] PKRU: 55555554
>> [60919.463622] Call Trace:
>> [60919.475617] <IRQ>
>> [60919.487122] ? update_load_avg+0x89/0x5d0
>> [60919.498478] ? update_load_avg+0x89/0x5d0
>> [60919.509822] ? account_entity_enqueue+0xc5/0xf0
>> [60919.520709] security_sock_rcv_skb+0x2a/0x40
>> [60919.531413] sk_filter_trim_cap+0x47/0x1b0
>> [60919.542178] ? kmem_cache_alloc+0x38/0x1b0
>> [60919.552444] sock_queue_rcv_skb+0x17/0x30
>> [60919.562477] raw_rcv+0x110/0x190 [can_raw]
>> [60919.572539] can_rcv_filter+0xbc/0x1b0 [can]
>> [60919.582173] can_receive+0x6b/0xb0 [can]
>> [60919.591595] can_rcv+0x31/0x70 [can]
>> [60919.600783] __netif_receive_skb_one_core+0x5a/0x80
>> [60919.609864] process_backlog+0x9b/0x150
>> [60919.618691] net_rx_action+0x156/0x400
>> [60919.627310] ? sched_clock_cpu+0xc/0xa0
>> [60919.635714] __do_softirq+0xe8/0x2e9
>> [60919.644161] do_softirq_own_stack+0x2a/0x40
>> [60919.652154] </IRQ>
>> [60919.659899] do_softirq.part.17+0x4f/0x60
>> [60919.667475] __local_bh_enable_ip+0x60/0x70
>> [60919.675089] __dev_queue_xmit+0x539/0x920
>> [60919.682267] ? finish_wait+0x80/0x80
>> [60919.689218] ? finish_wait+0x80/0x80
>> [60919.695886] ? sock_alloc_send_pskb+0x211/0x230
>> [60919.702395] ? can_send+0xe5/0x1f0 [can]
>> [60919.708882] can_send+0xe5/0x1f0 [can]
>> [60919.715037] raw_sendmsg+0x16d/0x268 [can_raw]
>>
>> It's because raw_setsockopt() concurrently with
>> unregister_netdevice_many(). Concurrent scenario as following.
>>
>> cpu0 cpu1
>> raw_bind
>> raw_setsockopt unregister_netdevice_many
>> unlist_netdevice
>> dev_get_by_index raw_notifier
>> raw_enable_filters ......
>> can_rx_register
>> can_rcv_list_find(..., net->can.rx_alldev_list)
>>
>> ......
>>
>> sock_close
>> raw_release(sock_a)
>>
>> ......
>>
>> can_receive
>> can_rcv_filter(net->can.rx_alldev_list, ...)
>> raw_rcv(skb, sock_a)
>> BUG
>>
>> After unlist_netdevice(), dev_get_by_index() return NULL in
>> raw_setsockopt(). Function raw_enable_filters() will add sock
>> and can_filter to net->can.rx_alldev_list. Then the sock is closed.
>> Followed by, we sock_sendmsg() to a new vcan device use the same
>> can_filter. Protocol stack match the old receiver whose sock has
>> been released on net->can.rx_alldev_list in can_rcv_filter().
>> Function raw_rcv() uses the freed sock. UAF BUG is triggered.
>>
>> We can find that the key issue is that net_device has not been
>> protected in raw_setsockopt(). Use rtnl_lock to protect net_device
>> in raw_setsockopt().
>>
>> Fixes: c18ce101f2e4 ("[CAN]: Add raw protocol")
>> Signed-off-by: Ziyang Xuan <[email protected]>
>> ---
>> net/can/raw.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/net/can/raw.c b/net/can/raw.c
>> index ed4fcb7ab0c3..a63e9915c66a 100644
>> --- a/net/can/raw.c
>> +++ b/net/can/raw.c
>> @@ -546,6 +546,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>> return -EFAULT;
>> }
>>
>> + rtnl_lock();
>> lock_sock(sk);
>>
>> if (ro->bound && ro->ifindex)
>> @@ -588,6 +589,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>> dev_put(dev);
>>
>> release_sock(sk);
>> + rtnl_unlock();
>>
>> break;
>>
>> @@ -600,6 +602,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>>
>> err_mask &= CAN_ERR_MASK;
>>
>> + rtnl_lock();
>> lock_sock(sk);
>>
>> if (ro->bound && ro->ifindex)
>> @@ -627,6 +630,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>> dev_put(dev);
>>
>> release_sock(sk);
>> + rtnl_unlock();
>>
>> break;
>>
>> --
>> 2.25.1
>>
>
>
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree. Please read:
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> for how to do this properly.
>
> </formletter>
>
Answering myself ...
On 21.07.21 08:35, Oliver Hartkopp wrote:
>
>
> On 21.07.21 06:53, Greg KH wrote:
>> On Wed, Jul 21, 2021 at 09:09:37AM +0800, Ziyang Xuan wrote:
>>> We get a bug during ltp can_filter test as following.
>>>
>>> ===========================================
>>> [60919.264984] BUG: unable to handle kernel NULL pointer dereference
>>> at 0000000000000010
>>> [60919.265223] PGD 8000003dda726067 P4D 8000003dda726067 PUD
>>> 3dda727067 PMD 0
>>> [60919.265443] Oops: 0000 [#1] SMP PTI
>>> [60919.265550] CPU: 30 PID: 3638365 Comm: can_filter Kdump: loaded
>>> Tainted: G W 4.19.90+ #1
>
> This kernel version 4.19.90 is definitely outdated.
>
> Can you please check your issue with the latest uptream kernel as this
> problem should have been fixed with this patch:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d0caedb759683041d9db82069937525999ada53
>
> ("can: bcm/raw/isotp: use per module netdevice notifier")
>
> Thanks!
I think my hint had a wrong assumption. The suggestion to add some
locking seems correct.
>>> [60919.266068] RIP: 0010:selinux_socket_sock_rcv_skb+0x3e/0x200
>>> [60919.293289] RSP: 0018:ffff8d53bfc03cf8 EFLAGS: 00010246
>>> [60919.307140] RAX: 0000000000000000 RBX: 000000000000001d RCX:
>>> 0000000000000007
>>> [60919.320756] RDX: 0000000000000001 RSI: ffff8d5104a8ed00 RDI:
>>> ffff8d53bfc03d30
>>> [60919.334319] RBP: ffff8d9338056800 R08: ffff8d53bfc29d80 R09:
>>> 0000000000000001
>>> [60919.347969] R10: ffff8d53bfc03ec0 R11: ffffb8526ef47c98 R12:
>>> ffff8d53bfc03d30
>>> [60919.350320] perf: interrupt took too long (3063 > 2500), lowering
>>> kernel.perf_event_max_sample_rate to 65000
>>> [60919.361148] R13: 0000000000000001 R14: ffff8d53bcf90000 R15:
>>> 0000000000000000
>>> [60919.361151] FS: 00007fb78b6b3600(0000) GS:ffff8d53bfc00000(0000)
>>> knlGS:0000000000000000
>>> [60919.400812] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [60919.413730] CR2: 0000000000000010 CR3: 0000003e3f784006 CR4:
>>> 00000000007606e0
>>> [60919.426479] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
>>> 0000000000000000
>>> [60919.439339] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
>>> 0000000000000400
>>> [60919.451608] PKRU: 55555554
>>> [60919.463622] Call Trace:
>>> [60919.475617] <IRQ>
>>> [60919.487122] ? update_load_avg+0x89/0x5d0
>>> [60919.498478] ? update_load_avg+0x89/0x5d0
>>> [60919.509822] ? account_entity_enqueue+0xc5/0xf0
>>> [60919.520709] security_sock_rcv_skb+0x2a/0x40
>>> [60919.531413] sk_filter_trim_cap+0x47/0x1b0
>>> [60919.542178] ? kmem_cache_alloc+0x38/0x1b0
>>> [60919.552444] sock_queue_rcv_skb+0x17/0x30
>>> [60919.562477] raw_rcv+0x110/0x190 [can_raw]
>>> [60919.572539] can_rcv_filter+0xbc/0x1b0 [can]
>>> [60919.582173] can_receive+0x6b/0xb0 [can]
>>> [60919.591595] can_rcv+0x31/0x70 [can]
>>> [60919.600783] __netif_receive_skb_one_core+0x5a/0x80
>>> [60919.609864] process_backlog+0x9b/0x150
>>> [60919.618691] net_rx_action+0x156/0x400
>>> [60919.627310] ? sched_clock_cpu+0xc/0xa0
>>> [60919.635714] __do_softirq+0xe8/0x2e9
>>> [60919.644161] do_softirq_own_stack+0x2a/0x40
>>> [60919.652154] </IRQ>
>>> [60919.659899] do_softirq.part.17+0x4f/0x60
>>> [60919.667475] __local_bh_enable_ip+0x60/0x70
>>> [60919.675089] __dev_queue_xmit+0x539/0x920
>>> [60919.682267] ? finish_wait+0x80/0x80
>>> [60919.689218] ? finish_wait+0x80/0x80
>>> [60919.695886] ? sock_alloc_send_pskb+0x211/0x230
>>> [60919.702395] ? can_send+0xe5/0x1f0 [can]
>>> [60919.708882] can_send+0xe5/0x1f0 [can]
>>> [60919.715037] raw_sendmsg+0x16d/0x268 [can_raw]
>>>
>>> It's because raw_setsockopt() concurrently with
>>> unregister_netdevice_many(). Concurrent scenario as following.
>>>
>>> cpu0 cpu1
>>> raw_bind
>>> raw_setsockopt unregister_netdevice_many
>>> unlist_netdevice
>>> dev_get_by_index raw_notifier
>>> raw_enable_filters ......
>>> can_rx_register
>>> can_rcv_list_find(..., net->can.rx_alldev_list)
>>>
>>> ......
>>>
>>> sock_close
>>> raw_release(sock_a)
>>>
>>> ......
>>>
>>> can_receive
>>> can_rcv_filter(net->can.rx_alldev_list, ...)
>>> raw_rcv(skb, sock_a)
>>> BUG
>>>
>>> After unlist_netdevice(), dev_get_by_index() return NULL in
>>> raw_setsockopt(). Function raw_enable_filters() will add sock
>>> and can_filter to net->can.rx_alldev_list.
Btw. this should not happen too!
dev_get_by_index() is executed depending on ro->ifindex which means
there should be a real network interface. When dev_get_by_index()
returns NULL this can considered to be wrong.
Adding a new filter to net->can.rx_alldev_list as a consequence is wrong
too.
>>> Then the sock is closed.
>>> Followed by, we sock_sendmsg() to a new vcan device use the same
>>> can_filter. Protocol stack match the old receiver whose sock has
>>> been released on net->can.rx_alldev_list in can_rcv_filter().
>>> Function raw_rcv() uses the freed sock. UAF BUG is triggered.
>>>
>>> We can find that the key issue is that net_device has not been
>>> protected in raw_setsockopt(). Use rtnl_lock to protect net_device
>>> in raw_setsockopt().
>>>
>>> Fixes: c18ce101f2e4 ("[CAN]: Add raw protocol")
>>> Signed-off-by: Ziyang Xuan <[email protected]>
Can you please resend the below patch as suggested by Greg KH and add my
Signed-off-by: Oliver Hartkopp <[email protected]>
as it also adds the dev_get_by_index() return check.
diff --git a/net/can/raw.c b/net/can/raw.c
index ed4fcb7ab0c3..d3cbc32036c7 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -544,14 +544,18 @@ static int raw_setsockopt(struct socket *sock, int
level, int optname,
} else if (count == 1) {
if (copy_from_sockptr(&sfilter, optval, sizeof(sfilter)))
return -EFAULT;
}
+ rtnl_lock();
lock_sock(sk);
- if (ro->bound && ro->ifindex)
+ if (ro->bound && ro->ifindex) {
dev = dev_get_by_index(sock_net(sk), ro->ifindex);
+ if (!dev)
+ goto out_fil;
+ }
if (ro->bound) {
/* (try to) register the new filters */
if (count == 1)
err = raw_enable_filters(sock_net(sk), dev, sk,
@@ -586,10 +590,11 @@ static int raw_setsockopt(struct socket *sock, int
level, int optname,
out_fil:
if (dev)
dev_put(dev);
release_sock(sk);
+ rtnl_unlock();
break;
case CAN_RAW_ERR_FILTER:
if (optlen != sizeof(err_mask))
@@ -598,14 +603,18 @@ static int raw_setsockopt(struct socket *sock, int
level, int optname,
if (copy_from_sockptr(&err_mask, optval, optlen))
return -EFAULT;
err_mask &= CAN_ERR_MASK;
+ rtnl_lock();
lock_sock(sk);
- if (ro->bound && ro->ifindex)
+ if (ro->bound && ro->ifindex) {
dev = dev_get_by_index(sock_net(sk), ro->ifindex);
+ if (!dev)
+ goto out_err;
+ }
/* remove current error mask */
if (ro->bound) {
/* (try to) register the new err_mask */
err = raw_enable_errfilter(sock_net(sk), dev, sk,
@@ -625,10 +634,11 @@ static int raw_setsockopt(struct socket *sock, int
level, int optname,
out_err:
if (dev)
dev_put(dev);
release_sock(sk);
+ rtnl_unlock();
break;
case CAN_RAW_LOOPBACK:
if (optlen != sizeof(ro->loopback))
Thanks for the finding!
Best regards,
Oliver
(..)
>>
>>
>> <formletter>
>>
>> This is not the correct way to submit patches for inclusion in the
>> stable kernel tree. Please read:
>>
>> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>> for how to do this properly.
>>
>> </formletter>
>>
On 7/21/2021 2:35 PM, Oliver Hartkopp wrote:
>
>
> On 21.07.21 06:53, Greg KH wrote:
>> On Wed, Jul 21, 2021 at 09:09:37AM +0800, Ziyang Xuan wrote:
>>> We get a bug during ltp can_filter test as following.
>>>
>>> ===========================================
>>> [60919.264984] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
>>> [60919.265223] PGD 8000003dda726067 P4D 8000003dda726067 PUD 3dda727067 PMD 0
>>> [60919.265443] Oops: 0000 [#1] SMP PTI
>>> [60919.265550] CPU: 30 PID: 3638365 Comm: can_filter Kdump: loaded Tainted: G W 4.19.90+ #1
>
> This kernel version 4.19.90 is definitely outdated.
>
> Can you please check your issue with the latest uptream kernel as this problem should have been fixed with this patch:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d0caedb759683041d9db82069937525999ada53
> ("can: bcm/raw/isotp: use per module netdevice notifier")
>
> Thanks!
I have tested it under the latest 5.14-rc2 kernel version which includes commit 8d0caedb7596 before I submit the patch.
Although I failed to get the vmcore-dmesg file after updating the kernel version to 5.14-rc2 to display here.
But we can get the conclusion according to the following debug messages and my problem analysis.
==========================================
[ 1048.953574] unlist_netdevice name[vcan0]
[ 1048.953661] raw_notify 283: enter, waiting
[ 1050.950967] raw_setsockopt 552: ro->bound[1] ro->ifindex[8] sk[ffff9420c5699800]
[ 1053.956002] can: receive list entry not found for dev any, id 000, mask 000
[ 1053.961989] can: receive list entry not found for dev vcan0, id 123, mask 7FF
raw_setsockopt() executes after unlist_netdevice() and before raw_notify().
The problem always exists.
>
>>> [60919.266068] RIP: 0010:selinux_socket_sock_rcv_skb+0x3e/0x200
>>> [60919.293289] RSP: 0018:ffff8d53bfc03cf8 EFLAGS: 00010246
>>> [60919.307140] RAX: 0000000000000000 RBX: 000000000000001d RCX: 0000000000000007
>>> [60919.320756] RDX: 0000000000000001 RSI: ffff8d5104a8ed00 RDI: ffff8d53bfc03d30
>>> [60919.334319] RBP: ffff8d9338056800 R08: ffff8d53bfc29d80 R09: 0000000000000001
>>> [60919.347969] R10: ffff8d53bfc03ec0 R11: ffffb8526ef47c98 R12: ffff8d53bfc03d30
>>> [60919.350320] perf: interrupt took too long (3063 > 2500), lowering kernel.perf_event_max_sample_rate to 65000
>>> [60919.361148] R13: 0000000000000001 R14: ffff8d53bcf90000 R15: 0000000000000000
>>> [60919.361151] FS: 00007fb78b6b3600(0000) GS:ffff8d53bfc00000(0000) knlGS:0000000000000000
>>> [60919.400812] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [60919.413730] CR2: 0000000000000010 CR3: 0000003e3f784006 CR4: 00000000007606e0
>>> [60919.426479] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>> [60919.439339] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>> [60919.451608] PKRU: 55555554
>>> [60919.463622] Call Trace:
>>> [60919.475617] <IRQ>
>>> [60919.487122] ? update_load_avg+0x89/0x5d0
>>> [60919.498478] ? update_load_avg+0x89/0x5d0
>>> [60919.509822] ? account_entity_enqueue+0xc5/0xf0
>>> [60919.520709] security_sock_rcv_skb+0x2a/0x40
>>> [60919.531413] sk_filter_trim_cap+0x47/0x1b0
>>> [60919.542178] ? kmem_cache_alloc+0x38/0x1b0
>>> [60919.552444] sock_queue_rcv_skb+0x17/0x30
>>> [60919.562477] raw_rcv+0x110/0x190 [can_raw]
>>> [60919.572539] can_rcv_filter+0xbc/0x1b0 [can]
>>> [60919.582173] can_receive+0x6b/0xb0 [can]
>>> [60919.591595] can_rcv+0x31/0x70 [can]
>>> [60919.600783] __netif_receive_skb_one_core+0x5a/0x80
>>> [60919.609864] process_backlog+0x9b/0x150
>>> [60919.618691] net_rx_action+0x156/0x400
>>> [60919.627310] ? sched_clock_cpu+0xc/0xa0
>>> [60919.635714] __do_softirq+0xe8/0x2e9
>>> [60919.644161] do_softirq_own_stack+0x2a/0x40
>>> [60919.652154] </IRQ>
>>> [60919.659899] do_softirq.part.17+0x4f/0x60
>>> [60919.667475] __local_bh_enable_ip+0x60/0x70
>>> [60919.675089] __dev_queue_xmit+0x539/0x920
>>> [60919.682267] ? finish_wait+0x80/0x80
>>> [60919.689218] ? finish_wait+0x80/0x80
>>> [60919.695886] ? sock_alloc_send_pskb+0x211/0x230
>>> [60919.702395] ? can_send+0xe5/0x1f0 [can]
>>> [60919.708882] can_send+0xe5/0x1f0 [can]
>>> [60919.715037] raw_sendmsg+0x16d/0x268 [can_raw]
>>>
>>> It's because raw_setsockopt() concurrently with
>>> unregister_netdevice_many(). Concurrent scenario as following.
>>>
>>> cpu0 cpu1
>>> raw_bind
>>> raw_setsockopt unregister_netdevice_many
>>> unlist_netdevice
>>> dev_get_by_index raw_notifier
>>> raw_enable_filters ......
>>> can_rx_register
>>> can_rcv_list_find(..., net->can.rx_alldev_list)
>>>
>>> ......
>>>
>>> sock_close
>>> raw_release(sock_a)
>>>
>>> ......
>>>
>>> can_receive
>>> can_rcv_filter(net->can.rx_alldev_list, ...)
>>> raw_rcv(skb, sock_a)
>>> BUG
>>>
>>> After unlist_netdevice(), dev_get_by_index() return NULL in
>>> raw_setsockopt(). Function raw_enable_filters() will add sock
>>> and can_filter to net->can.rx_alldev_list. Then the sock is closed.
>>> Followed by, we sock_sendmsg() to a new vcan device use the same
>>> can_filter. Protocol stack match the old receiver whose sock has
>>> been released on net->can.rx_alldev_list in can_rcv_filter().
>>> Function raw_rcv() uses the freed sock. UAF BUG is triggered.
>>>
>>> We can find that the key issue is that net_device has not been
>>> protected in raw_setsockopt(). Use rtnl_lock to protect net_device
>>> in raw_setsockopt().
>>>
>>> Fixes: c18ce101f2e4 ("[CAN]: Add raw protocol")
>>> Signed-off-by: Ziyang Xuan <[email protected]>
>>> ---
>>> net/can/raw.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/net/can/raw.c b/net/can/raw.c
>>> index ed4fcb7ab0c3..a63e9915c66a 100644
>>> --- a/net/can/raw.c
>>> +++ b/net/can/raw.c
>>> @@ -546,6 +546,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>>> return -EFAULT;
>>> }
>>> + rtnl_lock();
>>> lock_sock(sk);
>>> if (ro->bound && ro->ifindex)
>>> @@ -588,6 +589,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>>> dev_put(dev);
>>> release_sock(sk);
>>> + rtnl_unlock();
>>> break;
>>> @@ -600,6 +602,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>>> err_mask &= CAN_ERR_MASK;
>>> + rtnl_lock();
>>> lock_sock(sk);
>>> if (ro->bound && ro->ifindex)
>>> @@ -627,6 +630,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>>> dev_put(dev);
>>> release_sock(sk);
>>> + rtnl_unlock();
>>> break;
>>> --
>>> 2.25.1
>>>
>>
>>
>> <formletter>
>>
>> This is not the correct way to submit patches for inclusion in the
>> stable kernel tree. Please read:
>> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>> for how to do this properly.
>>
>> </formletter>
>>
> .
On 21.07.21 11:29, Ziyang Xuan (William) wrote:
> On 7/21/2021 2:35 PM, Oliver Hartkopp wrote:
>>
>>
>> On 21.07.21 06:53, Greg KH wrote:
>>> On Wed, Jul 21, 2021 at 09:09:37AM +0800, Ziyang Xuan wrote:
>>>> We get a bug during ltp can_filter test as following.
>>>>
>>>> ===========================================
>>>> [60919.264984] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
>>>> [60919.265223] PGD 8000003dda726067 P4D 8000003dda726067 PUD 3dda727067 PMD 0
>>>> [60919.265443] Oops: 0000 [#1] SMP PTI
>>>> [60919.265550] CPU: 30 PID: 3638365 Comm: can_filter Kdump: loaded Tainted: G W 4.19.90+ #1
>>
>> This kernel version 4.19.90 is definitely outdated.
>>
>> Can you please check your issue with the latest uptream kernel as this problem should have been fixed with this patch:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d0caedb759683041d9db82069937525999ada53
>> ("can: bcm/raw/isotp: use per module netdevice notifier")
>>
>> Thanks!
>
> I have tested it under the latest 5.14-rc2 kernel version which includes commit 8d0caedb7596 before I submit the patch.
> Although I failed to get the vmcore-dmesg file after updating the kernel version to 5.14-rc2 to display here.
> But we can get the conclusion according to the following debug messages and my problem analysis.
>
> ==========================================
> [ 1048.953574] unlist_netdevice name[vcan0]
> [ 1048.953661] raw_notify 283: enter, waiting
> [ 1050.950967] raw_setsockopt 552: ro->bound[1] ro->ifindex[8] sk[ffff9420c5699800]
> [ 1053.956002] can: receive list entry not found for dev any, id 000, mask 000
> [ 1053.961989] can: receive list entry not found for dev vcan0, id 123, mask 7FF
>
> raw_setsockopt() executes after unlist_netdevice() and before raw_notify().
> The problem always exists.
>
You are right!
In the meantime I sent a new reply to your original patch here:
https://lore.kernel.org/linux-can/[email protected]/
Thanks!
On 7/21/2021 5:24 PM, Oliver Hartkopp wrote:
> Answering myself ...
>
> On 21.07.21 08:35, Oliver Hartkopp wrote:
>>
>>
>> On 21.07.21 06:53, Greg KH wrote:
>>> On Wed, Jul 21, 2021 at 09:09:37AM +0800, Ziyang Xuan wrote:
>>>> We get a bug during ltp can_filter test as following.
>>>>
>>>> ===========================================
>>>> [60919.264984] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
>>>> [60919.265223] PGD 8000003dda726067 P4D 8000003dda726067 PUD 3dda727067 PMD 0
>>>> [60919.265443] Oops: 0000 [#1] SMP PTI
>>>> [60919.265550] CPU: 30 PID: 3638365 Comm: can_filter Kdump: loaded Tainted: G W 4.19.90+ #1
>>
>> This kernel version 4.19.90 is definitely outdated.
>>
>> Can you please check your issue with the latest uptream kernel as this problem should have been fixed with this patch:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d0caedb759683041d9db82069937525999ada53
>> ("can: bcm/raw/isotp: use per module netdevice notifier")
>>
>> Thanks!
>
> I think my hint had a wrong assumption. The suggestion to add some locking seems correct.
>
>>>> [60919.266068] RIP: 0010:selinux_socket_sock_rcv_skb+0x3e/0x200
>>>> [60919.293289] RSP: 0018:ffff8d53bfc03cf8 EFLAGS: 00010246
>>>> [60919.307140] RAX: 0000000000000000 RBX: 000000000000001d RCX: 0000000000000007
>>>> [60919.320756] RDX: 0000000000000001 RSI: ffff8d5104a8ed00 RDI: ffff8d53bfc03d30
>>>> [60919.334319] RBP: ffff8d9338056800 R08: ffff8d53bfc29d80 R09: 0000000000000001
>>>> [60919.347969] R10: ffff8d53bfc03ec0 R11: ffffb8526ef47c98 R12: ffff8d53bfc03d30
>>>> [60919.350320] perf: interrupt took too long (3063 > 2500), lowering kernel.perf_event_max_sample_rate to 65000
>>>> [60919.361148] R13: 0000000000000001 R14: ffff8d53bcf90000 R15: 0000000000000000
>>>> [60919.361151] FS: 00007fb78b6b3600(0000) GS:ffff8d53bfc00000(0000) knlGS:0000000000000000
>>>> [60919.400812] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> [60919.413730] CR2: 0000000000000010 CR3: 0000003e3f784006 CR4: 00000000007606e0
>>>> [60919.426479] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>>> [60919.439339] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>>> [60919.451608] PKRU: 55555554
>>>> [60919.463622] Call Trace:
>>>> [60919.475617] <IRQ>
>>>> [60919.487122] ? update_load_avg+0x89/0x5d0
>>>> [60919.498478] ? update_load_avg+0x89/0x5d0
>>>> [60919.509822] ? account_entity_enqueue+0xc5/0xf0
>>>> [60919.520709] security_sock_rcv_skb+0x2a/0x40
>>>> [60919.531413] sk_filter_trim_cap+0x47/0x1b0
>>>> [60919.542178] ? kmem_cache_alloc+0x38/0x1b0
>>>> [60919.552444] sock_queue_rcv_skb+0x17/0x30
>>>> [60919.562477] raw_rcv+0x110/0x190 [can_raw]
>>>> [60919.572539] can_rcv_filter+0xbc/0x1b0 [can]
>>>> [60919.582173] can_receive+0x6b/0xb0 [can]
>>>> [60919.591595] can_rcv+0x31/0x70 [can]
>>>> [60919.600783] __netif_receive_skb_one_core+0x5a/0x80
>>>> [60919.609864] process_backlog+0x9b/0x150
>>>> [60919.618691] net_rx_action+0x156/0x400
>>>> [60919.627310] ? sched_clock_cpu+0xc/0xa0
>>>> [60919.635714] __do_softirq+0xe8/0x2e9
>>>> [60919.644161] do_softirq_own_stack+0x2a/0x40
>>>> [60919.652154] </IRQ>
>>>> [60919.659899] do_softirq.part.17+0x4f/0x60
>>>> [60919.667475] __local_bh_enable_ip+0x60/0x70
>>>> [60919.675089] __dev_queue_xmit+0x539/0x920
>>>> [60919.682267] ? finish_wait+0x80/0x80
>>>> [60919.689218] ? finish_wait+0x80/0x80
>>>> [60919.695886] ? sock_alloc_send_pskb+0x211/0x230
>>>> [60919.702395] ? can_send+0xe5/0x1f0 [can]
>>>> [60919.708882] can_send+0xe5/0x1f0 [can]
>>>> [60919.715037] raw_sendmsg+0x16d/0x268 [can_raw]
>>>>
>>>> It's because raw_setsockopt() concurrently with
>>>> unregister_netdevice_many(). Concurrent scenario as following.
>>>>
>>>> cpu0 cpu1
>>>> raw_bind
>>>> raw_setsockopt unregister_netdevice_many
>>>> unlist_netdevice
>>>> dev_get_by_index raw_notifier
>>>> raw_enable_filters ......
>>>> can_rx_register
>>>> can_rcv_list_find(..., net->can.rx_alldev_list)
>>>>
>>>> ......
>>>>
>>>> sock_close
>>>> raw_release(sock_a)
>>>>
>>>> ......
>>>>
>>>> can_receive
>>>> can_rcv_filter(net->can.rx_alldev_list, ...)
>>>> raw_rcv(skb, sock_a)
>>>> BUG
>>>>
>>>> After unlist_netdevice(), dev_get_by_index() return NULL in
>>>> raw_setsockopt(). Function raw_enable_filters() will add sock
>>>> and can_filter to net->can.rx_alldev_list.
>
> Btw. this should not happen too!
>
> dev_get_by_index() is executed depending on ro->ifindex which means there should be a real network interface. When dev_get_by_index() returns NULL this can considered to be wrong.
>
> Adding a new filter to net->can.rx_alldev_list as a consequence is wrong too.
>
>>>> Then the sock is closed.
>>>> Followed by, we sock_sendmsg() to a new vcan device use the same
>>>> can_filter. Protocol stack match the old receiver whose sock has
>>>> been released on net->can.rx_alldev_list in can_rcv_filter().
>>>> Function raw_rcv() uses the freed sock. UAF BUG is triggered.
>>>>
>>>> We can find that the key issue is that net_device has not been
>>>> protected in raw_setsockopt(). Use rtnl_lock to protect net_device
>>>> in raw_setsockopt().
>>>>
>>>> Fixes: c18ce101f2e4 ("[CAN]: Add raw protocol")
>>>> Signed-off-by: Ziyang Xuan <[email protected]>
>
> Can you please resend the below patch as suggested by Greg KH and add my
>
> Signed-off-by: Oliver Hartkopp <[email protected]>
>
> as it also adds the dev_get_by_index() return check.
>
> diff --git a/net/can/raw.c b/net/can/raw.c
> index ed4fcb7ab0c3..d3cbc32036c7 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -544,14 +544,18 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> } else if (count == 1) {
> if (copy_from_sockptr(&sfilter, optval, sizeof(sfilter)))
> return -EFAULT;
> }
>
> + rtnl_lock();
> lock_sock(sk);
>
> - if (ro->bound && ro->ifindex)
> + if (ro->bound && ro->ifindex) {
> dev = dev_get_by_index(sock_net(sk), ro->ifindex);
> + if (!dev)
> + goto out_fil;
> + }
At first, I also use this modification. After discussion with my partner, we found that
it is impossible scenario if we use rtnl_lock to protect net_device object.
We can see two sequences:
1. raw_setsockopt first get rtnl_lock, unregister_netdevice_many later.
It can be simplified to add the filter in raw_setsockopt, then remove the filter in raw_notify.
2. unregister_netdevice_many first get rtnl_lock, raw_setsockopt later.
raw_notify will set ro->ifindex, ro->bound and ro->count to zero firstly. The filter will not
be added to any filter_list in raw_notify.
So I selected the current modification. Do you think so?
My first modification as following:
diff --git a/net/can/raw.c b/net/can/raw.c
index ed4fcb7ab0c3..a0ce4908317f 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -546,10 +546,16 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
return -EFAULT;
}
+ rtnl_lock();
lock_sock(sk);
- if (ro->bound && ro->ifindex)
+ if (ro->bound && ro->ifindex) {
dev = dev_get_by_index(sock_net(sk), ro->ifindex);
+ if (!dev) {
+ err = -ENODEV;
+ goto out_fil;
+ }
+ }
if (ro->bound) {
/* (try to) register the new filters */
@@ -559,11 +565,8 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
else
err = raw_enable_filters(sock_net(sk), dev, sk,
filter, count);
- if (err) {
- if (count > 1)
- kfree(filter);
+ if (err)
goto out_fil;
- }
/* remove old filter registrations */
raw_disable_filters(sock_net(sk), dev, sk, ro->filter,
@@ -584,10 +587,14 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
ro->count = count;
out_fil:
+ if (err && count > 1)
+ kfree(filter);
+
if (dev)
dev_put(dev);
release_sock(sk);
+ rtnl_unlock();
break;
@@ -600,10 +607,16 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
err_mask &= CAN_ERR_MASK;
+ rtnl_lock();
lock_sock(sk);
- if (ro->bound && ro->ifindex)
+ if (ro->bound && ro->ifindex) {
dev = dev_get_by_index(sock_net(sk), ro->ifindex);
+ if (!dev) {
+ err = -ENODEV;
+ goto out_err;
+ }
+ }
/* remove current error mask */
if (ro->bound) {
@@ -627,6 +640,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
dev_put(dev);
release_sock(sk);
+ rtnl_unlock();
break;
>
> if (ro->bound) {
> /* (try to) register the new filters */
> if (count == 1)
> err = raw_enable_filters(sock_net(sk), dev, sk,
> @@ -586,10 +590,11 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> out_fil:
> if (dev)
> dev_put(dev);
>
> release_sock(sk);
> + rtnl_unlock();
>
> break;
>
> case CAN_RAW_ERR_FILTER:
> if (optlen != sizeof(err_mask))
> @@ -598,14 +603,18 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> if (copy_from_sockptr(&err_mask, optval, optlen))
> return -EFAULT;
>
> err_mask &= CAN_ERR_MASK;
>
> + rtnl_lock();
> lock_sock(sk);
>
> - if (ro->bound && ro->ifindex)
> + if (ro->bound && ro->ifindex) {
> dev = dev_get_by_index(sock_net(sk), ro->ifindex);
> + if (!dev)
> + goto out_err;
> + }
>
> /* remove current error mask */
> if (ro->bound) {
> /* (try to) register the new err_mask */
> err = raw_enable_errfilter(sock_net(sk), dev, sk,
> @@ -625,10 +634,11 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> out_err:
> if (dev)
> dev_put(dev);
>
> release_sock(sk);
> + rtnl_unlock();
>
> break;
>
> case CAN_RAW_LOOPBACK:
> if (optlen != sizeof(ro->loopback))
>
>
>
>
> Thanks for the finding!
>
> Best regards,
> Oliver
>
> (..)
>>>
>>>
>>> <formletter>
>>>
>>> This is not the correct way to submit patches for inclusion in the
>>> stable kernel tree. Please read:
>>> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>>> for how to do this properly.
>>>
>>> </formletter>
>>>
> .
On 21.07.21 13:37, Ziyang Xuan (William) wrote:
> On 7/21/2021 5:24 PM, Oliver Hartkopp wrote:
>>
>> Can you please resend the below patch as suggested by Greg KH and add my
>>
>> Signed-off-by: Oliver Hartkopp <[email protected]>
>>
>> as it also adds the dev_get_by_index() return check.
>>
>> diff --git a/net/can/raw.c b/net/can/raw.c
>> index ed4fcb7ab0c3..d3cbc32036c7 100644
>> --- a/net/can/raw.c
>> +++ b/net/can/raw.c
>> @@ -544,14 +544,18 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>> } else if (count == 1) {
>> if (copy_from_sockptr(&sfilter, optval, sizeof(sfilter)))
>> return -EFAULT;
>> }
>>
>> + rtnl_lock();
>> lock_sock(sk);
>>
>> - if (ro->bound && ro->ifindex)
>> + if (ro->bound && ro->ifindex) {
>> dev = dev_get_by_index(sock_net(sk), ro->ifindex);
>> + if (!dev)
>> + goto out_fil;
>> + }
> At first, I also use this modification. After discussion with my partner, we found that
> it is impossible scenario if we use rtnl_lock to protect net_device object.
> We can see two sequences:
> 1. raw_setsockopt first get rtnl_lock, unregister_netdevice_many later.
> It can be simplified to add the filter in raw_setsockopt, then remove the filter in raw_notify.
>
> 2. unregister_netdevice_many first get rtnl_lock, raw_setsockopt later.
> raw_notify will set ro->ifindex, ro->bound and ro->count to zero firstly. The filter will not
> be added to any filter_list in raw_notify.
>
> So I selected the current modification. Do you think so?
>
> My first modification as following:
>
> diff --git a/net/can/raw.c b/net/can/raw.c
> index ed4fcb7ab0c3..a0ce4908317f 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -546,10 +546,16 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> return -EFAULT;
> }
>
> + rtnl_lock();
> lock_sock(sk);
>
> - if (ro->bound && ro->ifindex)
> + if (ro->bound && ro->ifindex) {
> dev = dev_get_by_index(sock_net(sk), ro->ifindex);
> + if (!dev) {
> + err = -ENODEV;
> + goto out_fil;
> + }
> + }
>
> if (ro->bound) {
> /* (try to) register the new filters */
> @@ -559,11 +565,8 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> else
> err = raw_enable_filters(sock_net(sk), dev, sk,
> filter, count);
> - if (err) {
> - if (count > 1)
> - kfree(filter);
> + if (err)
> goto out_fil;
> - }
>
> /* remove old filter registrations */
> raw_disable_filters(sock_net(sk), dev, sk, ro->filter,
> @@ -584,10 +587,14 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> ro->count = count;
>
> out_fil:
> + if (err && count > 1)
> + kfree(filter);
> +
Setting the err variable to -ENODEV is a good idea but I do not like the
movement of kfree(filter).
The kfree() has a tight relation inside the if-statement for ro->bound
which makes it easier to understand.
Regards,
Oliver
ps. your patches have less context than mine. Do you have different
settings for -U<n>, --unified=<n> for 'git diff' ?
> if (dev)
> dev_put(dev);
>
> release_sock(sk);
> + rtnl_unlock();
>
> break;
>
> @@ -600,10 +607,16 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>
> err_mask &= CAN_ERR_MASK;
>
> + rtnl_lock();
> lock_sock(sk);
>
> - if (ro->bound && ro->ifindex)
> + if (ro->bound && ro->ifindex) {
> dev = dev_get_by_index(sock_net(sk), ro->ifindex);
> + if (!dev) {
> + err = -ENODEV;
> + goto out_err;
> + }
> + }
>
> /* remove current error mask */
> if (ro->bound) {
> @@ -627,6 +640,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> dev_put(dev);
>
> release_sock(sk);
> + rtnl_unlock();
>
> break;
>
On 7/21/2021 11:13 PM, Oliver Hartkopp wrote:
>
>
> On 21.07.21 13:37, Ziyang Xuan (William) wrote:
>> On 7/21/2021 5:24 PM, Oliver Hartkopp wrote:
>
>>>
>>> Can you please resend the below patch as suggested by Greg KH and add my
>>>
>>> Signed-off-by: Oliver Hartkopp <[email protected]>
>>>
>>> as it also adds the dev_get_by_index() return check.
>>>
>>> diff --git a/net/can/raw.c b/net/can/raw.c
>>> index ed4fcb7ab0c3..d3cbc32036c7 100644
>>> --- a/net/can/raw.c
>>> +++ b/net/can/raw.c
>>> @@ -544,14 +544,18 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>>> } else if (count == 1) {
>>> if (copy_from_sockptr(&sfilter, optval, sizeof(sfilter)))
>>> return -EFAULT;
>>> }
>>>
>>> + rtnl_lock();
>>> lock_sock(sk);
>>>
>>> - if (ro->bound && ro->ifindex)
>>> + if (ro->bound && ro->ifindex) {
>>> dev = dev_get_by_index(sock_net(sk), ro->ifindex);
>>> + if (!dev)
>>> + goto out_fil;
>>> + }
>> At first, I also use this modification. After discussion with my partner, we found that
>> it is impossible scenario if we use rtnl_lock to protect net_device object.
>> We can see two sequences:
>> 1. raw_setsockopt first get rtnl_lock, unregister_netdevice_many later.
>> It can be simplified to add the filter in raw_setsockopt, then remove the filter in raw_notify.
>>
>> 2. unregister_netdevice_many first get rtnl_lock, raw_setsockopt later.
>> raw_notify will set ro->ifindex, ro->bound and ro->count to zero firstly. The filter will not
>> be added to any filter_list in raw_notify.
>>
>> So I selected the current modification. Do you think so?
>>
>> My first modification as following:
>>
>> diff --git a/net/can/raw.c b/net/can/raw.c
>> index ed4fcb7ab0c3..a0ce4908317f 100644
>> --- a/net/can/raw.c
>> +++ b/net/can/raw.c
>> @@ -546,10 +546,16 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>> return -EFAULT;
>> }
>>
>> + rtnl_lock();
>> lock_sock(sk);
>>
>> - if (ro->bound && ro->ifindex)
>> + if (ro->bound && ro->ifindex) {
>> dev = dev_get_by_index(sock_net(sk), ro->ifindex);
>> + if (!dev) {
>> + err = -ENODEV;
>> + goto out_fil;
>> + }
>> + }
>>
>> if (ro->bound) {
>> /* (try to) register the new filters */
>> @@ -559,11 +565,8 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>> else
>> err = raw_enable_filters(sock_net(sk), dev, sk,
>> filter, count);
>> - if (err) {
>> - if (count > 1)
>> - kfree(filter);
>> + if (err)
>> goto out_fil;
>> - }
>>
>> /* remove old filter registrations */
>> raw_disable_filters(sock_net(sk), dev, sk, ro->filter,
>> @@ -584,10 +587,14 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>> ro->count = count;
>>
>> out_fil:
>> + if (err && count > 1)
>> + kfree(filter);
>> +
>
> Setting the err variable to -ENODEV is a good idea but I do not like the movement of kfree(filter).
>
> The kfree() has a tight relation inside the if-statement for ro->bound which makes it easier to understand.
>
> Regards,
> Oliver
I will submit the v2 patch for the problem according to your suggestions. Than you.