LinuxLists.cc - [PATCH v2] xfrm: add NULL check in xfrm_update_ae

2023-07-21 15:24:12

Subject: [PATCH v2] xfrm: add NULL check in xfrm_update_ae_params

Normally, x->replay_esn and x->preplay_esn should be allocated at
xfrm_alloc_replay_state_esn(...) in xfrm_state_construct(...), hence the
xfrm_update_ae_params(...) is okay to update them. However, the current
implementation of xfrm_new_ae(...) allows a malicious user to directly
dereference a NULL pointer and crash the kernel like below.

BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 8253067 P4D 8253067 PUD 8e0e067 PMD 0
Oops: 0002 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 PID: 98 Comm: poc.npd Not tainted 6.4.0-rc7-00072-gdad9774deaf1 #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.o4
RIP: 0010:memcpy_orig+0xad/0x140
Code: e8 4c 89 5f e0 48 8d 7f e0 73 d2 83 c2 20 48 29 d6 48 29 d7 83 fa 10 72 34 4c 8b 06 4c 8b 4e 08 c
RSP: 0018:ffff888008f57658 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff888008bd0000 RCX: ffffffff8238e571
RDX: 0000000000000018 RSI: ffff888007f64844 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888008f57818
R13: ffff888007f64aa4 R14: 0000000000000000 R15: 0000000000000000
FS: 00000000014013c0(0000) GS:ffff88806d600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000054d8000 CR4: 00000000000006f0
Call Trace:
<TASK>
? __die+0x1f/0x70
? page_fault_oops+0x1e8/0x500
? __pfx_is_prefetch.constprop.0+0x10/0x10
? __pfx_page_fault_oops+0x10/0x10
? _raw_spin_unlock_irqrestore+0x11/0x40
? fixup_exception+0x36/0x460
? _raw_spin_unlock_irqrestore+0x11/0x40
? exc_page_fault+0x5e/0xc0
? asm_exc_page_fault+0x26/0x30
? xfrm_update_ae_params+0xd1/0x260
? memcpy_orig+0xad/0x140
? __pfx__raw_spin_lock_bh+0x10/0x10
xfrm_update_ae_params+0xe7/0x260
xfrm_new_ae+0x298/0x4e0
? __pfx_xfrm_new_ae+0x10/0x10
? __pfx_xfrm_new_ae+0x10/0x10
xfrm_user_rcv_msg+0x25a/0x410
? __pfx_xfrm_user_rcv_msg+0x10/0x10
? __alloc_skb+0xcf/0x210
? stack_trace_save+0x90/0xd0
? filter_irq_stacks+0x1c/0x70
? __stack_depot_save+0x39/0x4e0
? __kasan_slab_free+0x10a/0x190
? kmem_cache_free+0x9c/0x340
? netlink_recvmsg+0x23c/0x660
? sock_recvmsg+0xeb/0xf0
? __sys_recvfrom+0x13c/0x1f0
? __x64_sys_recvfrom+0x71/0x90
? do_syscall_64+0x3f/0x90
? entry_SYSCALL_64_after_hwframe+0x72/0xdc
? copyout+0x3e/0x50
netlink_rcv_skb+0xd6/0x210
? __pfx_xfrm_user_rcv_msg+0x10/0x10
? __pfx_netlink_rcv_skb+0x10/0x10
? __pfx_sock_has_perm+0x10/0x10
? mutex_lock+0x8d/0xe0
? __pfx_mutex_lock+0x10/0x10
xfrm_netlink_rcv+0x44/0x50
netlink_unicast+0x36f/0x4c0
? __pfx_netlink_unicast+0x10/0x10
? netlink_recvmsg+0x500/0x660
netlink_sendmsg+0x3b7/0x700

This Null-ptr-deref bug is assigned CVE-2023-3772. And this commit
adds additional NULL check in xfrm_update_ae_params to fix the NPD.

Fixes: d8647b79c3b7 ("xfrm: Add user interface for esn and big anti-replay windows")
Signed-off-by: Lin Ma <[email protected]>
---
V1 -> V2: fix some typos: impelementation -> implementation,
frm_update_ae_params -> xfrm_update_ae_params

net/xfrm/xfrm_user.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index c34a2a06ca94..bf2564967501 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -628,7 +628,7 @@ static void xfrm_update_ae_params(struct xfrm_state *x, struct nlattr **attrs,
struct nlattr *rt = attrs[XFRMA_REPLAY_THRESH];
struct nlattr *mt = attrs[XFRMA_MTIMER_THRESH];

- if (re) {
+ if (re && x->replay_esn && x->preplay_esn) {
struct xfrm_replay_state_esn *replay_esn;
replay_esn = nla_data(re);
memcpy(x->replay_esn, replay_esn,
--
2.17.1

2023-07-24 11:36:35

by Leon Romanovsky

[permalink] [raw]

Subject: Re: [PATCH v2] xfrm: add NULL check in xfrm_update_ae_params

On Fri, Jul 21, 2023 at 10:51:03PM +0800, Lin Ma wrote:
> Normally, x->replay_esn and x->preplay_esn should be allocated at
> xfrm_alloc_replay_state_esn(...) in xfrm_state_construct(...), hence the
> xfrm_update_ae_params(...) is okay to update them. However, the current
> implementation of xfrm_new_ae(...) allows a malicious user to directly
> dereference a NULL pointer and crash the kernel like below.
>
> BUG: kernel NULL pointer dereference, address: 0000000000000000
> PGD 8253067 P4D 8253067 PUD 8e0e067 PMD 0
> Oops: 0002 [#1] PREEMPT SMP KASAN NOPTI
> CPU: 0 PID: 98 Comm: poc.npd Not tainted 6.4.0-rc7-00072-gdad9774deaf1 #8
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.o4
> RIP: 0010:memcpy_orig+0xad/0x140
> Code: e8 4c 89 5f e0 48 8d 7f e0 73 d2 83 c2 20 48 29 d6 48 29 d7 83 fa 10 72 34 4c 8b 06 4c 8b 4e 08 c
> RSP: 0018:ffff888008f57658 EFLAGS: 00000202
> RAX: 0000000000000000 RBX: ffff888008bd0000 RCX: ffffffff8238e571
> RDX: 0000000000000018 RSI: ffff888007f64844 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff888008f57818
> R13: ffff888007f64aa4 R14: 0000000000000000 R15: 0000000000000000
> FS: 00000000014013c0(0000) GS:ffff88806d600000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 00000000054d8000 CR4: 00000000000006f0
> Call Trace:
> <TASK>
> ? __die+0x1f/0x70
> ? page_fault_oops+0x1e8/0x500
> ? __pfx_is_prefetch.constprop.0+0x10/0x10
> ? __pfx_page_fault_oops+0x10/0x10
> ? _raw_spin_unlock_irqrestore+0x11/0x40
> ? fixup_exception+0x36/0x460
> ? _raw_spin_unlock_irqrestore+0x11/0x40
> ? exc_page_fault+0x5e/0xc0
> ? asm_exc_page_fault+0x26/0x30
> ? xfrm_update_ae_params+0xd1/0x260
> ? memcpy_orig+0xad/0x140
> ? __pfx__raw_spin_lock_bh+0x10/0x10
> xfrm_update_ae_params+0xe7/0x260
> xfrm_new_ae+0x298/0x4e0
> ? __pfx_xfrm_new_ae+0x10/0x10
> ? __pfx_xfrm_new_ae+0x10/0x10
> xfrm_user_rcv_msg+0x25a/0x410
> ? __pfx_xfrm_user_rcv_msg+0x10/0x10
> ? __alloc_skb+0xcf/0x210
> ? stack_trace_save+0x90/0xd0
> ? filter_irq_stacks+0x1c/0x70
> ? __stack_depot_save+0x39/0x4e0
> ? __kasan_slab_free+0x10a/0x190
> ? kmem_cache_free+0x9c/0x340
> ? netlink_recvmsg+0x23c/0x660
> ? sock_recvmsg+0xeb/0xf0
> ? __sys_recvfrom+0x13c/0x1f0
> ? __x64_sys_recvfrom+0x71/0x90
> ? do_syscall_64+0x3f/0x90
> ? entry_SYSCALL_64_after_hwframe+0x72/0xdc
> ? copyout+0x3e/0x50
> netlink_rcv_skb+0xd6/0x210
> ? __pfx_xfrm_user_rcv_msg+0x10/0x10
> ? __pfx_netlink_rcv_skb+0x10/0x10
> ? __pfx_sock_has_perm+0x10/0x10
> ? mutex_lock+0x8d/0xe0
> ? __pfx_mutex_lock+0x10/0x10
> xfrm_netlink_rcv+0x44/0x50
> netlink_unicast+0x36f/0x4c0
> ? __pfx_netlink_unicast+0x10/0x10
> ? netlink_recvmsg+0x500/0x660
> netlink_sendmsg+0x3b7/0x700
>
> This Null-ptr-deref bug is assigned CVE-2023-3772. And this commit
> adds additional NULL check in xfrm_update_ae_params to fix the NPD.
>
> Fixes: d8647b79c3b7 ("xfrm: Add user interface for esn and big anti-replay windows")
> Signed-off-by: Lin Ma <[email protected]>
> ---
> V1 -> V2: fix some typos: impelementation -> implementation,
> frm_update_ae_params -> xfrm_update_ae_params
>
> net/xfrm/xfrm_user.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
> index c34a2a06ca94..bf2564967501 100644
> --- a/net/xfrm/xfrm_user.c
> +++ b/net/xfrm/xfrm_user.c
> @@ -628,7 +628,7 @@ static void xfrm_update_ae_params(struct xfrm_state *x, struct nlattr **attrs,
> struct nlattr *rt = attrs[XFRMA_REPLAY_THRESH];
> struct nlattr *mt = attrs[XFRMA_MTIMER_THRESH];
>
> - if (re) {
> + if (re && x->replay_esn && x->preplay_esn) {

If x->replay_esn is valid, x->preplay_esn will be valid too.

Thanks,
Reviewed-by: Leon Romanovsky <[email protected]>

2023-08-01 10:19:14

by Steffen Klassert

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