* [PATCH v2 net] tipc: Fix use-after-free in tipc_mon_reinit_self().
@ 2025-11-07 6:40 Kuniyuki Iwashima
2025-11-10 19:11 ` Simon Horman
2025-11-11 2:30 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Kuniyuki Iwashima @ 2025-11-07 6:40 UTC (permalink / raw)
To: Jon Maloy, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni
Cc: Simon Horman, Hoang Le, Kuniyuki Iwashima, Kuniyuki Iwashima,
netdev, tipc-discussion, syzbot+d7dad7fd4b3921104957
syzbot reported use-after-free of tipc_net(net)->monitors[]
in tipc_mon_reinit_self(). [0]
The array is protected by RTNL, but tipc_mon_reinit_self()
iterates over it without RTNL.
tipc_mon_reinit_self() is called from tipc_net_finalize(),
which is always under RTNL except for tipc_net_finalize_work().
Let's hold RTNL in tipc_net_finalize_work().
[0]:
BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
Read of size 1 at addr ffff88805eae1030 by task kworker/0:7/5989
CPU: 0 UID: 0 PID: 5989 Comm: kworker/0:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events tipc_net_finalize_work
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
__kasan_check_byte+0x2a/0x40 mm/kasan/common.c:568
kasan_check_byte include/linux/kasan.h:399 [inline]
lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5842
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
rtlock_slowlock kernel/locking/rtmutex.c:1894 [inline]
rwbase_rtmutex_lock_state kernel/locking/spinlock_rt.c:160 [inline]
rwbase_write_lock+0xd3/0x7e0 kernel/locking/rwbase_rt.c:244
rt_write_lock+0x76/0x110 kernel/locking/spinlock_rt.c:243
write_lock_bh include/linux/rwlock_rt.h:99 [inline]
tipc_mon_reinit_self+0x79/0x430 net/tipc/monitor.c:718
tipc_net_finalize+0x115/0x190 net/tipc/net.c:140
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Allocated by task 6089:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405
kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x1a8/0x320 mm/slub.c:4407
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
tipc_mon_create+0xc3/0x4d0 net/tipc/monitor.c:657
tipc_enable_bearer net/tipc/bearer.c:357 [inline]
__tipc_nl_bearer_enable+0xe16/0x13f0 net/tipc/bearer.c:1047
__tipc_nl_compat_doit net/tipc/netlink_compat.c:371 [inline]
tipc_nl_compat_doit+0x3bc/0x5f0 net/tipc/netlink_compat.c:393
tipc_nl_compat_handle net/tipc/netlink_compat.c:-1 [inline]
tipc_nl_compat_recv+0x83c/0xbe0 net/tipc/netlink_compat.c:1321
genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:714 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:729
____sys_sendmsg+0x508/0x820 net/socket.c:2614
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
__sys_sendmsg net/socket.c:2700 [inline]
__do_sys_sendmsg net/socket.c:2705 [inline]
__se_sys_sendmsg net/socket.c:2703 [inline]
__x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2703
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 6088:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:243 [inline]
__kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2422 [inline]
slab_free mm/slub.c:4695 [inline]
kfree+0x195/0x550 mm/slub.c:4894
tipc_l2_device_event+0x380/0x650 net/tipc/bearer.c:-1
notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
call_netdevice_notifiers net/core/dev.c:2281 [inline]
unregister_netdevice_many_notify+0x14d7/0x1fe0 net/core/dev.c:12166
unregister_netdevice_many net/core/dev.c:12229 [inline]
unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:12073
unregister_netdevice include/linux/netdevice.h:3385 [inline]
__tun_detach+0xe4d/0x1620 drivers/net/tun.c:621
tun_detach drivers/net/tun.c:637 [inline]
tun_chr_close+0x10d/0x1c0 drivers/net/tun.c:3433
__fput+0x458/0xa80 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Fixes: 46cb01eeeb86 ("tipc: update mon's self addr when node addr generated")
Reported-by: syzbot+d7dad7fd4b3921104957@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/690c323a.050a0220.baf87.007f.GAE@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
v2: Wrap tipc_net_finalize_work() with RTNL (Jakub)
v1: https://lore.kernel.org/netdev/20251106053309.401275-1-kuniyu@google.com/
---
net/tipc/net.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/tipc/net.c b/net/tipc/net.c
index 0e95572e56b4..7e65d0b0c4a8 100644
--- a/net/tipc/net.c
+++ b/net/tipc/net.c
@@ -145,7 +145,9 @@ void tipc_net_finalize_work(struct work_struct *work)
{
struct tipc_net *tn = container_of(work, struct tipc_net, work);
+ rtnl_lock();
tipc_net_finalize(tipc_link_net(tn->bcl), tn->trial_addr);
+ rtnl_unlock();
}
void tipc_net_stop(struct net *net)
--
2.51.2.1041.gc1ab5b90ca-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2 net] tipc: Fix use-after-free in tipc_mon_reinit_self().
2025-11-07 6:40 [PATCH v2 net] tipc: Fix use-after-free in tipc_mon_reinit_self() Kuniyuki Iwashima
@ 2025-11-10 19:11 ` Simon Horman
2025-11-11 2:30 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Simon Horman @ 2025-11-10 19:11 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: Jon Maloy, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Hoang Le, Kuniyuki Iwashima, netdev, tipc-discussion,
syzbot+d7dad7fd4b3921104957
On Fri, Nov 07, 2025 at 06:40:25AM +0000, Kuniyuki Iwashima wrote:
> syzbot reported use-after-free of tipc_net(net)->monitors[]
> in tipc_mon_reinit_self(). [0]
>
> The array is protected by RTNL, but tipc_mon_reinit_self()
> iterates over it without RTNL.
>
> tipc_mon_reinit_self() is called from tipc_net_finalize(),
> which is always under RTNL except for tipc_net_finalize_work().
>
> Let's hold RTNL in tipc_net_finalize_work().
>
> [0]:
> BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
> BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
> Read of size 1 at addr ffff88805eae1030 by task kworker/0:7/5989
>
> CPU: 0 UID: 0 PID: 5989 Comm: kworker/0:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
> Workqueue: events tipc_net_finalize_work
> Call Trace:
> <TASK>
> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
> print_address_description mm/kasan/report.c:378 [inline]
> print_report+0xca/0x240 mm/kasan/report.c:482
> kasan_report+0x118/0x150 mm/kasan/report.c:595
> __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:568
> kasan_check_byte include/linux/kasan.h:399 [inline]
> lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5842
> __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
> _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
> rtlock_slowlock kernel/locking/rtmutex.c:1894 [inline]
> rwbase_rtmutex_lock_state kernel/locking/spinlock_rt.c:160 [inline]
> rwbase_write_lock+0xd3/0x7e0 kernel/locking/rwbase_rt.c:244
> rt_write_lock+0x76/0x110 kernel/locking/spinlock_rt.c:243
> write_lock_bh include/linux/rwlock_rt.h:99 [inline]
> tipc_mon_reinit_self+0x79/0x430 net/tipc/monitor.c:718
> tipc_net_finalize+0x115/0x190 net/tipc/net.c:140
> process_one_work kernel/workqueue.c:3236 [inline]
> process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
> worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
> kthread+0x70e/0x8a0 kernel/kthread.c:463
> ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> </TASK>
>
> Allocated by task 6089:
> kasan_save_stack mm/kasan/common.c:47 [inline]
> kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
> poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
> __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405
> kasan_kmalloc include/linux/kasan.h:260 [inline]
> __kmalloc_cache_noprof+0x1a8/0x320 mm/slub.c:4407
> kmalloc_noprof include/linux/slab.h:905 [inline]
> kzalloc_noprof include/linux/slab.h:1039 [inline]
> tipc_mon_create+0xc3/0x4d0 net/tipc/monitor.c:657
> tipc_enable_bearer net/tipc/bearer.c:357 [inline]
> __tipc_nl_bearer_enable+0xe16/0x13f0 net/tipc/bearer.c:1047
> __tipc_nl_compat_doit net/tipc/netlink_compat.c:371 [inline]
> tipc_nl_compat_doit+0x3bc/0x5f0 net/tipc/netlink_compat.c:393
> tipc_nl_compat_handle net/tipc/netlink_compat.c:-1 [inline]
> tipc_nl_compat_recv+0x83c/0xbe0 net/tipc/netlink_compat.c:1321
> genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
> genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
> genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
> netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552
> genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
> netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
> netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1346
> netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
> sock_sendmsg_nosec net/socket.c:714 [inline]
> __sock_sendmsg+0x21c/0x270 net/socket.c:729
> ____sys_sendmsg+0x508/0x820 net/socket.c:2614
> ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
> __sys_sendmsg net/socket.c:2700 [inline]
> __do_sys_sendmsg net/socket.c:2705 [inline]
> __se_sys_sendmsg net/socket.c:2703 [inline]
> __x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2703
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Freed by task 6088:
> kasan_save_stack mm/kasan/common.c:47 [inline]
> kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
> kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
> poison_slab_object mm/kasan/common.c:243 [inline]
> __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
> kasan_slab_free include/linux/kasan.h:233 [inline]
> slab_free_hook mm/slub.c:2422 [inline]
> slab_free mm/slub.c:4695 [inline]
> kfree+0x195/0x550 mm/slub.c:4894
> tipc_l2_device_event+0x380/0x650 net/tipc/bearer.c:-1
> notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
> call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
> call_netdevice_notifiers net/core/dev.c:2281 [inline]
> unregister_netdevice_many_notify+0x14d7/0x1fe0 net/core/dev.c:12166
> unregister_netdevice_many net/core/dev.c:12229 [inline]
> unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:12073
> unregister_netdevice include/linux/netdevice.h:3385 [inline]
> __tun_detach+0xe4d/0x1620 drivers/net/tun.c:621
> tun_detach drivers/net/tun.c:637 [inline]
> tun_chr_close+0x10d/0x1c0 drivers/net/tun.c:3433
> __fput+0x458/0xa80 fs/file_table.c:468
> task_work_run+0x1d4/0x260 kernel/task_work.c:227
> resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
> exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
> exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
> syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
> syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
> do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Fixes: 46cb01eeeb86 ("tipc: update mon's self addr when node addr generated")
> Reported-by: syzbot+d7dad7fd4b3921104957@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/690c323a.050a0220.baf87.007f.GAE@google.com/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> ---
> v2: Wrap tipc_net_finalize_work() with RTNL (Jakub)
> v1: https://lore.kernel.org/netdev/20251106053309.401275-1-kuniyu@google.com/
Thanks Iwashima-san,
I agree with the analysis above.
Reviewed-by: Simon Horman <horms@kernel.org>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2 net] tipc: Fix use-after-free in tipc_mon_reinit_self().
2025-11-07 6:40 [PATCH v2 net] tipc: Fix use-after-free in tipc_mon_reinit_self() Kuniyuki Iwashima
2025-11-10 19:11 ` Simon Horman
@ 2025-11-11 2:30 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2025-11-11 2:30 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: jmaloy, davem, edumazet, kuba, pabeni, horms, hoang.h.le,
kuni1840, netdev, tipc-discussion, syzbot+d7dad7fd4b3921104957
Hello:
This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Fri, 7 Nov 2025 06:40:25 +0000 you wrote:
> syzbot reported use-after-free of tipc_net(net)->monitors[]
> in tipc_mon_reinit_self(). [0]
>
> The array is protected by RTNL, but tipc_mon_reinit_self()
> iterates over it without RTNL.
>
> tipc_mon_reinit_self() is called from tipc_net_finalize(),
> which is always under RTNL except for tipc_net_finalize_work().
>
> [...]
Here is the summary with links:
- [v2,net] tipc: Fix use-after-free in tipc_mon_reinit_self().
https://git.kernel.org/netdev/net/c/0725e6afb551
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-11-07 6:40 [PATCH v2 net] tipc: Fix use-after-free in tipc_mon_reinit_self() Kuniyuki Iwashima
2025-11-10 19:11 ` Simon Horman
2025-11-11 2:30 ` patchwork-bot+netdevbpf
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