There are UAF bugs in rose_heartbeat_expiry(), rose_timer_expiry()
and rose_idletimer_expiry(). The root cause is that del_timer()
could not stop the timer handler that is running and the refcount
of sock is not managed properly.
One of the UAF bugs is shown below:
(thread 1) | (thread 2)
| rose_bind
| rose_connect
| rose_start_heartbeat
rose_release | (wait a time)
case ROSE_STATE_0 |
rose_destroy_socket | rose_heartbeat_expiry
rose_stop_heartbeat |
sock_put(sk) | ...
sock_put(sk) // FREE |
| bh_lock_sock(sk) // USE
The sock is deallocated by sock_put() in rose_release() and
then used by bh_lock_sock() in rose_heartbeat_expiry().
Although rose_destroy_socket() calls rose_stop_heartbeat(),
it could not stop the timer that is running.
The KASAN report triggered by POC is shown below:
BUG: KASAN: use-after-free in _raw_spin_lock+0x5a/0x110
Write of size 4 at addr ffff88800ae59098 by task swapper/3/0
...
Call Trace:
<IRQ>
dump_stack_lvl+0xbf/0xee
print_address_description+0x7b/0x440
print_report+0x101/0x230
? irq_work_single+0xbb/0x140
? _raw_spin_lock+0x5a/0x110
kasan_report+0xed/0x120
? _raw_spin_lock+0x5a/0x110
kasan_check_range+0x2bd/0x2e0
_raw_spin_lock+0x5a/0x110
rose_heartbeat_expiry+0x39/0x370
? rose_start_heartbeat+0xb0/0xb0
call_timer_fn+0x2d/0x1c0
? rose_start_heartbeat+0xb0/0xb0
expire_timers+0x1f3/0x320
__run_timers+0x3ff/0x4d0
run_timer_softirq+0x41/0x80
__do_softirq+0x233/0x544
irq_exit_rcu+0x41/0xa0
sysvec_apic_timer_interrupt+0x8c/0xb0
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1b/0x20
RIP: 0010:default_idle+0xb/0x10
RSP: 0018:ffffc9000012fea0 EFLAGS: 00000202
RAX: 000000000000bcae RBX: ffff888006660f00 RCX: 000000000000bcae
RDX: 0000000000000001 RSI: ffffffff843a11c0 RDI: ffffffff843a1180
RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed100da36d46
R10: dfffe9100da36d47 R11: ffffffff83cf0950 R12: 0000000000000000
R13: 1ffff11000ccc1e0 R14: ffffffff8542af28 R15: dffffc0000000000
...
Allocated by task 146:
__kasan_kmalloc+0xc4/0xf0
sk_prot_alloc+0xdd/0x1a0
sk_alloc+0x2d/0x4e0
rose_create+0x7b/0x330
__sock_create+0x2dd/0x640
__sys_socket+0xc7/0x270
__x64_sys_socket+0x71/0x80
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x46/0xb0
Freed by task 152:
kasan_set_track+0x4c/0x70
kasan_set_free_info+0x1f/0x40
____kasan_slab_free+0x124/0x190
kfree+0xd3/0x270
__sk_destruct+0x314/0x460
rose_release+0x2fa/0x3b0
sock_close+0xcb/0x230
__fput+0x2d9/0x650
task_work_run+0xd6/0x160
exit_to_user_mode_loop+0xc7/0xd0
exit_to_user_mode_prepare+0x4e/0x80
syscall_exit_to_user_mode+0x20/0x40
do_syscall_64+0x4f/0x90
entry_SYSCALL_64_after_hwframe+0x46/0xb0
This patch adds refcount of sock when we use functions
such as rose_start_heartbeat() and so on to start timer,
and decreases the refcount of sock when timer is finished
or deleted by functions such as rose_stop_heartbeat()
and so on. As a result, the UAF bugs could be mitigated.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Duoming Zhou <[email protected]>
Tested-by: Duoming Zhou <[email protected]>
---
net/rose/rose_timer.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/net/rose/rose_timer.c b/net/rose/rose_timer.c
index b3138fc2e55..18d1912520b 100644
--- a/net/rose/rose_timer.c
+++ b/net/rose/rose_timer.c
@@ -36,7 +36,7 @@ void rose_start_heartbeat(struct sock *sk)
sk->sk_timer.function = rose_heartbeat_expiry;
sk->sk_timer.expires = jiffies + 5 * HZ;
- add_timer(&sk->sk_timer);
+ sk_reset_timer(sk, &sk->sk_timer, sk->sk_timer.expires);
}
void rose_start_t1timer(struct sock *sk)
@@ -48,7 +48,7 @@ void rose_start_t1timer(struct sock *sk)
rose->timer.function = rose_timer_expiry;
rose->timer.expires = jiffies + rose->t1;
- add_timer(&rose->timer);
+ sk_reset_timer(sk, &rose->timer, rose->timer.expires);
}
void rose_start_t2timer(struct sock *sk)
@@ -60,7 +60,7 @@ void rose_start_t2timer(struct sock *sk)
rose->timer.function = rose_timer_expiry;
rose->timer.expires = jiffies + rose->t2;
- add_timer(&rose->timer);
+ sk_reset_timer(sk, &rose->timer, rose->timer.expires);
}
void rose_start_t3timer(struct sock *sk)
@@ -72,7 +72,7 @@ void rose_start_t3timer(struct sock *sk)
rose->timer.function = rose_timer_expiry;
rose->timer.expires = jiffies + rose->t3;
- add_timer(&rose->timer);
+ sk_reset_timer(sk, &rose->timer, rose->timer.expires);
}
void rose_start_hbtimer(struct sock *sk)
@@ -84,7 +84,7 @@ void rose_start_hbtimer(struct sock *sk)
rose->timer.function = rose_timer_expiry;
rose->timer.expires = jiffies + rose->hb;
- add_timer(&rose->timer);
+ sk_reset_timer(sk, &rose->timer, rose->timer.expires);
}
void rose_start_idletimer(struct sock *sk)
@@ -97,23 +97,23 @@ void rose_start_idletimer(struct sock *sk)
rose->idletimer.function = rose_idletimer_expiry;
rose->idletimer.expires = jiffies + rose->idle;
- add_timer(&rose->idletimer);
+ sk_reset_timer(sk, &rose->idletimer, rose->idletimer.expires);
}
}
void rose_stop_heartbeat(struct sock *sk)
{
- del_timer(&sk->sk_timer);
+ sk_stop_timer(sk, &sk->sk_timer);
}
void rose_stop_timer(struct sock *sk)
{
- del_timer(&rose_sk(sk)->timer);
+ sk_stop_timer(sk, &rose_sk(sk)->timer);
}
void rose_stop_idletimer(struct sock *sk)
{
- del_timer(&rose_sk(sk)->idletimer);
+ sk_stop_timer(sk, &rose_sk(sk)->idletimer);
}
static void rose_heartbeat_expiry(struct timer_list *t)
@@ -130,6 +130,7 @@ static void rose_heartbeat_expiry(struct timer_list *t)
(sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_DEAD))) {
bh_unlock_sock(sk);
rose_destroy_socket(sk);
+ sock_put(sk);
return;
}
break;
@@ -152,6 +153,7 @@ static void rose_heartbeat_expiry(struct timer_list *t)
rose_start_heartbeat(sk);
bh_unlock_sock(sk);
+ sock_put(sk);
}
static void rose_timer_expiry(struct timer_list *t)
@@ -181,6 +183,7 @@ static void rose_timer_expiry(struct timer_list *t)
break;
}
bh_unlock_sock(sk);
+ sock_put(sk);
}
static void rose_idletimer_expiry(struct timer_list *t)
@@ -205,4 +208,5 @@ static void rose_idletimer_expiry(struct timer_list *t)
sock_set_flag(sk, SOCK_DEAD);
}
bh_unlock_sock(sk);
+ sock_put(sk);
}
--
2.17.1
On Wed, 2022-06-22 at 12:01 +0800, Duoming Zhou wrote:
> There are UAF bugs in rose_heartbeat_expiry(), rose_timer_expiry()
> and rose_idletimer_expiry(). The root cause is that del_timer()
> could not stop the timer handler that is running and the refcount
> of sock is not managed properly.
>
> One of the UAF bugs is shown below:
>
> (thread 1) | (thread 2)
> | rose_bind
> | rose_connect
> | rose_start_heartbeat
> rose_release | (wait a time)
> case ROSE_STATE_0 |
> rose_destroy_socket | rose_heartbeat_expiry
> rose_stop_heartbeat |
> sock_put(sk) | ...
> sock_put(sk) // FREE |
> | bh_lock_sock(sk) // USE
>
> The sock is deallocated by sock_put() in rose_release() and
> then used by bh_lock_sock() in rose_heartbeat_expiry().
>
> Although rose_destroy_socket() calls rose_stop_heartbeat(),
> it could not stop the timer that is running.
>
> The KASAN report triggered by POC is shown below:
>
> BUG: KASAN: use-after-free in _raw_spin_lock+0x5a/0x110
> Write of size 4 at addr ffff88800ae59098 by task swapper/3/0
> ...
> Call Trace:
> <IRQ>
> dump_stack_lvl+0xbf/0xee
> print_address_description+0x7b/0x440
> print_report+0x101/0x230
> ? irq_work_single+0xbb/0x140
> ? _raw_spin_lock+0x5a/0x110
> kasan_report+0xed/0x120
> ? _raw_spin_lock+0x5a/0x110
> kasan_check_range+0x2bd/0x2e0
> _raw_spin_lock+0x5a/0x110
> rose_heartbeat_expiry+0x39/0x370
> ? rose_start_heartbeat+0xb0/0xb0
> call_timer_fn+0x2d/0x1c0
> ? rose_start_heartbeat+0xb0/0xb0
> expire_timers+0x1f3/0x320
> __run_timers+0x3ff/0x4d0
> run_timer_softirq+0x41/0x80
> __do_softirq+0x233/0x544
> irq_exit_rcu+0x41/0xa0
> sysvec_apic_timer_interrupt+0x8c/0xb0
> </IRQ>
> <TASK>
> asm_sysvec_apic_timer_interrupt+0x1b/0x20
> RIP: 0010:default_idle+0xb/0x10
> RSP: 0018:ffffc9000012fea0 EFLAGS: 00000202
> RAX: 000000000000bcae RBX: ffff888006660f00 RCX: 000000000000bcae
> RDX: 0000000000000001 RSI: ffffffff843a11c0 RDI: ffffffff843a1180
> RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed100da36d46
> R10: dfffe9100da36d47 R11: ffffffff83cf0950 R12: 0000000000000000
> R13: 1ffff11000ccc1e0 R14: ffffffff8542af28 R15: dffffc0000000000
> ...
> Allocated by task 146:
> __kasan_kmalloc+0xc4/0xf0
> sk_prot_alloc+0xdd/0x1a0
> sk_alloc+0x2d/0x4e0
> rose_create+0x7b/0x330
> __sock_create+0x2dd/0x640
> __sys_socket+0xc7/0x270
> __x64_sys_socket+0x71/0x80
> do_syscall_64+0x43/0x90
> entry_SYSCALL_64_after_hwframe+0x46/0xb0
>
> Freed by task 152:
> kasan_set_track+0x4c/0x70
> kasan_set_free_info+0x1f/0x40
> ____kasan_slab_free+0x124/0x190
> kfree+0xd3/0x270
> __sk_destruct+0x314/0x460
> rose_release+0x2fa/0x3b0
> sock_close+0xcb/0x230
> __fput+0x2d9/0x650
> task_work_run+0xd6/0x160
> exit_to_user_mode_loop+0xc7/0xd0
> exit_to_user_mode_prepare+0x4e/0x80
> syscall_exit_to_user_mode+0x20/0x40
> do_syscall_64+0x4f/0x90
> entry_SYSCALL_64_after_hwframe+0x46/0xb0
>
> This patch adds refcount of sock when we use functions
> such as rose_start_heartbeat() and so on to start timer,
> and decreases the refcount of sock when timer is finished
> or deleted by functions such as rose_stop_heartbeat()
> and so on. As a result, the UAF bugs could be mitigated.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Duoming Zhou <[email protected]>
> Tested-by: Duoming Zhou <[email protected]>
> ---
> net/rose/rose_timer.c | 22 +++++++++++++---------
> 1 file changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/net/rose/rose_timer.c b/net/rose/rose_timer.c
> index b3138fc2e55..18d1912520b 100644
> --- a/net/rose/rose_timer.c
> +++ b/net/rose/rose_timer.c
> @@ -36,7 +36,7 @@ void rose_start_heartbeat(struct sock *sk)
> sk->sk_timer.function = rose_heartbeat_expiry;
> sk->sk_timer.expires = jiffies + 5 * HZ;
>
> - add_timer(&sk->sk_timer);
> + sk_reset_timer(sk, &sk->sk_timer, sk->sk_timer.expires);
> }
>
> void rose_start_t1timer(struct sock *sk)
> @@ -48,7 +48,7 @@ void rose_start_t1timer(struct sock *sk)
> rose->timer.function = rose_timer_expiry;
> rose->timer.expires = jiffies + rose->t1;
>
> - add_timer(&rose->timer);
> + sk_reset_timer(sk, &rose->timer, rose->timer.expires);
> }
>
> void rose_start_t2timer(struct sock *sk)
> @@ -60,7 +60,7 @@ void rose_start_t2timer(struct sock *sk)
> rose->timer.function = rose_timer_expiry;
> rose->timer.expires = jiffies + rose->t2;
>
> - add_timer(&rose->timer);
> + sk_reset_timer(sk, &rose->timer, rose->timer.expires);
> }
>
> void rose_start_t3timer(struct sock *sk)
> @@ -72,7 +72,7 @@ void rose_start_t3timer(struct sock *sk)
> rose->timer.function = rose_timer_expiry;
> rose->timer.expires = jiffies + rose->t3;
>
> - add_timer(&rose->timer);
> + sk_reset_timer(sk, &rose->timer, rose->timer.expires);
> }
>
> void rose_start_hbtimer(struct sock *sk)
> @@ -84,7 +84,7 @@ void rose_start_hbtimer(struct sock *sk)
> rose->timer.function = rose_timer_expiry;
> rose->timer.expires = jiffies + rose->hb;
>
> - add_timer(&rose->timer);
> + sk_reset_timer(sk, &rose->timer, rose->timer.expires);
> }
>
> void rose_start_idletimer(struct sock *sk)
> @@ -97,23 +97,23 @@ void rose_start_idletimer(struct sock *sk)
> rose->idletimer.function = rose_idletimer_expiry;
> rose->idletimer.expires = jiffies + rose->idle;
>
> - add_timer(&rose->idletimer);
> + sk_reset_timer(sk, &rose->idletimer, rose->idletimer.expires);
A few lines above there is still a 'del_timer(&rose->idletimer);' call
which must be converted to sk_stop_timer(), otherwise there will be a
possible sk reference leak.
There are other del_timer(&rose->timer) that need conversion.
Thanks
Paolo
Hello,
On Thu, 23 Jun 2022 11:13:41 +0200 Paolo Abeni wrote:
> > There are UAF bugs in rose_heartbeat_expiry(), rose_timer_expiry()
> > and rose_idletimer_expiry(). The root cause is that del_timer()
> > could not stop the timer handler that is running and the refcount
> > of sock is not managed properly.
> >
> > One of the UAF bugs is shown below:
> >
> > (thread 1) | (thread 2)
> > | rose_bind
> > | rose_connect
> > | rose_start_heartbeat
> > rose_release | (wait a time)
> > case ROSE_STATE_0 |
> > rose_destroy_socket | rose_heartbeat_expiry
> > rose_stop_heartbeat |
> > sock_put(sk) | ...
> > sock_put(sk) // FREE |
> > | bh_lock_sock(sk) // USE
> >
> > The sock is deallocated by sock_put() in rose_release() and
> > then used by bh_lock_sock() in rose_heartbeat_expiry().
> >
> > Although rose_destroy_socket() calls rose_stop_heartbeat(),
> > it could not stop the timer that is running.
> >
> > The KASAN report triggered by POC is shown below:
> >
> > BUG: KASAN: use-after-free in _raw_spin_lock+0x5a/0x110
> > Write of size 4 at addr ffff88800ae59098 by task swapper/3/0
> > ...
> > Call Trace:
> > <IRQ>
> > dump_stack_lvl+0xbf/0xee
> > print_address_description+0x7b/0x440
> > print_report+0x101/0x230
> > ? irq_work_single+0xbb/0x140
> > ? _raw_spin_lock+0x5a/0x110
> > kasan_report+0xed/0x120
> > ? _raw_spin_lock+0x5a/0x110
> > kasan_check_range+0x2bd/0x2e0
> > _raw_spin_lock+0x5a/0x110
> > rose_heartbeat_expiry+0x39/0x370
> > ? rose_start_heartbeat+0xb0/0xb0
> > call_timer_fn+0x2d/0x1c0
> > ? rose_start_heartbeat+0xb0/0xb0
> > expire_timers+0x1f3/0x320
> > __run_timers+0x3ff/0x4d0
> > run_timer_softirq+0x41/0x80
> > __do_softirq+0x233/0x544
> > irq_exit_rcu+0x41/0xa0
> > sysvec_apic_timer_interrupt+0x8c/0xb0
> > </IRQ>
> > <TASK>
> > asm_sysvec_apic_timer_interrupt+0x1b/0x20
> > RIP: 0010:default_idle+0xb/0x10
> > RSP: 0018:ffffc9000012fea0 EFLAGS: 00000202
> > RAX: 000000000000bcae RBX: ffff888006660f00 RCX: 000000000000bcae
> > RDX: 0000000000000001 RSI: ffffffff843a11c0 RDI: ffffffff843a1180
> > RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed100da36d46
> > R10: dfffe9100da36d47 R11: ffffffff83cf0950 R12: 0000000000000000
> > R13: 1ffff11000ccc1e0 R14: ffffffff8542af28 R15: dffffc0000000000
> > ...
> > Allocated by task 146:
> > __kasan_kmalloc+0xc4/0xf0
> > sk_prot_alloc+0xdd/0x1a0
> > sk_alloc+0x2d/0x4e0
> > rose_create+0x7b/0x330
> > __sock_create+0x2dd/0x640
> > __sys_socket+0xc7/0x270
> > __x64_sys_socket+0x71/0x80
> > do_syscall_64+0x43/0x90
> > entry_SYSCALL_64_after_hwframe+0x46/0xb0
> >
> > Freed by task 152:
> > kasan_set_track+0x4c/0x70
> > kasan_set_free_info+0x1f/0x40
> > ____kasan_slab_free+0x124/0x190
> > kfree+0xd3/0x270
> > __sk_destruct+0x314/0x460
> > rose_release+0x2fa/0x3b0
> > sock_close+0xcb/0x230
> > __fput+0x2d9/0x650
> > task_work_run+0xd6/0x160
> > exit_to_user_mode_loop+0xc7/0xd0
> > exit_to_user_mode_prepare+0x4e/0x80
> > syscall_exit_to_user_mode+0x20/0x40
> > do_syscall_64+0x4f/0x90
> > entry_SYSCALL_64_after_hwframe+0x46/0xb0
> >
> > This patch adds refcount of sock when we use functions
> > such as rose_start_heartbeat() and so on to start timer,
> > and decreases the refcount of sock when timer is finished
> > or deleted by functions such as rose_stop_heartbeat()
> > and so on. As a result, the UAF bugs could be mitigated.
> >
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Signed-off-by: Duoming Zhou <[email protected]>
> > Tested-by: Duoming Zhou <[email protected]>
> > ---
> > net/rose/rose_timer.c | 22 +++++++++++++---------
> > 1 file changed, 13 insertions(+), 9 deletions(-)
> >
> > diff --git a/net/rose/rose_timer.c b/net/rose/rose_timer.c
> > index b3138fc2e55..18d1912520b 100644
> > --- a/net/rose/rose_timer.c
> > +++ b/net/rose/rose_timer.c
> > @@ -36,7 +36,7 @@ void rose_start_heartbeat(struct sock *sk)
> > sk->sk_timer.function = rose_heartbeat_expiry;
> > sk->sk_timer.expires = jiffies + 5 * HZ;
> >
> > - add_timer(&sk->sk_timer);
> > + sk_reset_timer(sk, &sk->sk_timer, sk->sk_timer.expires);
> > }
> >
> > void rose_start_t1timer(struct sock *sk)
> > @@ -48,7 +48,7 @@ void rose_start_t1timer(struct sock *sk)
> > rose->timer.function = rose_timer_expiry;
> > rose->timer.expires = jiffies + rose->t1;
> >
> > - add_timer(&rose->timer);
> > + sk_reset_timer(sk, &rose->timer, rose->timer.expires);
> > }
> >
> > void rose_start_t2timer(struct sock *sk)
> > @@ -60,7 +60,7 @@ void rose_start_t2timer(struct sock *sk)
> > rose->timer.function = rose_timer_expiry;
> > rose->timer.expires = jiffies + rose->t2;
> >
> > - add_timer(&rose->timer);
> > + sk_reset_timer(sk, &rose->timer, rose->timer.expires);
> > }
> >
> > void rose_start_t3timer(struct sock *sk)
> > @@ -72,7 +72,7 @@ void rose_start_t3timer(struct sock *sk)
> > rose->timer.function = rose_timer_expiry;
> > rose->timer.expires = jiffies + rose->t3;
> >
> > - add_timer(&rose->timer);
> > + sk_reset_timer(sk, &rose->timer, rose->timer.expires);
> > }
> >
> > void rose_start_hbtimer(struct sock *sk)
> > @@ -84,7 +84,7 @@ void rose_start_hbtimer(struct sock *sk)
> > rose->timer.function = rose_timer_expiry;
> > rose->timer.expires = jiffies + rose->hb;
> >
> > - add_timer(&rose->timer);
> > + sk_reset_timer(sk, &rose->timer, rose->timer.expires);
> > }
> >
> > void rose_start_idletimer(struct sock *sk)
> > @@ -97,23 +97,23 @@ void rose_start_idletimer(struct sock *sk)
> > rose->idletimer.function = rose_idletimer_expiry;
> > rose->idletimer.expires = jiffies + rose->idle;
> >
> > - add_timer(&rose->idletimer);
> > + sk_reset_timer(sk, &rose->idletimer, rose->idletimer.expires);
>
> A few lines above there is still a 'del_timer(&rose->idletimer);' call
> which must be converted to sk_stop_timer(), otherwise there will be a
> possible sk reference leak.
>
> There are other del_timer(&rose->timer) that need conversion.
Thank you for your time and suggestions! I will convert 'del_timer(&rose->idletimer);'
and so on to sk_stop_timer().
Best regards,
Duoming Zhou