* [PATCH v1 net] rtnetlink: Fix bad unlock balance in do_setlink().
@ 2025-04-07 16:42 Kuniyuki Iwashima
2025-04-07 16:57 ` Stanislav Fomichev
2025-04-08 19:51 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Kuniyuki Iwashima @ 2025-04-07 16:42 UTC (permalink / raw)
To: David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni
Cc: Simon Horman, Stanislav Fomichev, Kuniyuki Iwashima,
Kuniyuki Iwashima, netdev, syzbot+45016fe295243a7882d3
When validate_linkmsg() fails in do_setlink(), we jump to the errout
label and calls netdev_unlock_ops() even though we have not called
netdev_lock_ops() as reported by syzbot. [0]
Let's return an error directly in such a case.
[0]
WARNING: bad unlock balance detected!
6.14.0-syzkaller-12504-g8bc251e5d874 #0 Not tainted
syz-executor814/5834 is trying to release lock (&dev_instance_lock_key) at:
[<ffffffff89f41f56>] netdev_unlock include/linux/netdevice.h:2756 [inline]
[<ffffffff89f41f56>] netdev_unlock_ops include/net/netdev_lock.h:48 [inline]
[<ffffffff89f41f56>] do_setlink+0xc26/0x43a0 net/core/rtnetlink.c:3406
but there are no more locks to release!
other info that might help us debug this:
1 lock held by syz-executor814/5834:
#0: ffffffff900fc408 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#0: ffffffff900fc408 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
#0: ffffffff900fc408 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xd68/0x1fe0 net/core/rtnetlink.c:4064
stack backtrace:
CPU: 0 UID: 0 PID: 5834 Comm: syz-executor814 Not tainted 6.14.0-syzkaller-12504-g8bc251e5d874 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_unlock_imbalance_bug+0x185/0x1a0 kernel/locking/lockdep.c:5296
__lock_release kernel/locking/lockdep.c:5535 [inline]
lock_release+0x1ed/0x3e0 kernel/locking/lockdep.c:5887
__mutex_unlock_slowpath+0xee/0x800 kernel/locking/mutex.c:907
netdev_unlock include/linux/netdevice.h:2756 [inline]
netdev_unlock_ops include/net/netdev_lock.h:48 [inline]
do_setlink+0xc26/0x43a0 net/core/rtnetlink.c:3406
rtnl_group_changelink net/core/rtnetlink.c:3783 [inline]
__rtnl_newlink net/core/rtnetlink.c:3937 [inline]
rtnl_newlink+0x1619/0x1fe0 net/core/rtnetlink.c:4065
rtnetlink_rcv_msg+0x80f/0xd70 net/core/rtnetlink.c:6955
netlink_rcv_skb+0x208/0x480 net/netlink/af_netlink.c:2534
netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
netlink_unicast+0x7f8/0x9a0 net/netlink/af_netlink.c:1339
netlink_sendmsg+0x8c3/0xcd0 net/netlink/af_netlink.c:1883
sock_sendmsg_nosec net/socket.c:712 [inline]
__sock_sendmsg+0x221/0x270 net/socket.c:727
____sys_sendmsg+0x523/0x860 net/socket.c:2566
___sys_sendmsg net/socket.c:2620 [inline]
__sys_sendmsg+0x271/0x360 net/socket.c:2652
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8427b614a9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff9b59f3a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fff9b59f578 RCX: 00007f8427b614a9
RDX: 0000000000000000 RSI: 0000200000000300 RDI: 0000000000000004
RBP: 00007f8427bd4610 R08: 000000000000000c R09: 00007fff9b59f578
R10: 000000000000001b R11: 0000000000000246 R12: 0000000000000001
R13:
Fixes: 4c975fd70002 ("net: hold instance lock during NETDEV_REGISTER/UP")
Reported-by: syzbot+45016fe295243a7882d3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=45016fe295243a7882d3
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
net/core/rtnetlink.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index c23852835050..925d634f724e 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3027,7 +3027,7 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev,
err = validate_linkmsg(dev, tb, extack);
if (err < 0)
- goto errout;
+ return err;
if (tb[IFLA_IFNAME])
nla_strscpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
--
2.48.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v1 net] rtnetlink: Fix bad unlock balance in do_setlink().
2025-04-07 16:42 [PATCH v1 net] rtnetlink: Fix bad unlock balance in do_setlink() Kuniyuki Iwashima
@ 2025-04-07 16:57 ` Stanislav Fomichev
2025-04-08 19:51 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Stanislav Fomichev @ 2025-04-07 16:57 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman, Stanislav Fomichev, Kuniyuki Iwashima, netdev,
syzbot+45016fe295243a7882d3
On 04/07, Kuniyuki Iwashima wrote:
> When validate_linkmsg() fails in do_setlink(), we jump to the errout
> label and calls netdev_unlock_ops() even though we have not called
> netdev_lock_ops() as reported by syzbot. [0]
>
> Let's return an error directly in such a case.
>
> [0]
> WARNING: bad unlock balance detected!
> 6.14.0-syzkaller-12504-g8bc251e5d874 #0 Not tainted
>
> syz-executor814/5834 is trying to release lock (&dev_instance_lock_key) at:
> [<ffffffff89f41f56>] netdev_unlock include/linux/netdevice.h:2756 [inline]
> [<ffffffff89f41f56>] netdev_unlock_ops include/net/netdev_lock.h:48 [inline]
> [<ffffffff89f41f56>] do_setlink+0xc26/0x43a0 net/core/rtnetlink.c:3406
> but there are no more locks to release!
>
> other info that might help us debug this:
> 1 lock held by syz-executor814/5834:
> #0: ffffffff900fc408 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
> #0: ffffffff900fc408 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
> #0: ffffffff900fc408 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xd68/0x1fe0 net/core/rtnetlink.c:4064
>
> stack backtrace:
> CPU: 0 UID: 0 PID: 5834 Comm: syz-executor814 Not tainted 6.14.0-syzkaller-12504-g8bc251e5d874 #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
> print_unlock_imbalance_bug+0x185/0x1a0 kernel/locking/lockdep.c:5296
> __lock_release kernel/locking/lockdep.c:5535 [inline]
> lock_release+0x1ed/0x3e0 kernel/locking/lockdep.c:5887
> __mutex_unlock_slowpath+0xee/0x800 kernel/locking/mutex.c:907
> netdev_unlock include/linux/netdevice.h:2756 [inline]
> netdev_unlock_ops include/net/netdev_lock.h:48 [inline]
> do_setlink+0xc26/0x43a0 net/core/rtnetlink.c:3406
> rtnl_group_changelink net/core/rtnetlink.c:3783 [inline]
> __rtnl_newlink net/core/rtnetlink.c:3937 [inline]
> rtnl_newlink+0x1619/0x1fe0 net/core/rtnetlink.c:4065
> rtnetlink_rcv_msg+0x80f/0xd70 net/core/rtnetlink.c:6955
> netlink_rcv_skb+0x208/0x480 net/netlink/af_netlink.c:2534
> netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
> netlink_unicast+0x7f8/0x9a0 net/netlink/af_netlink.c:1339
> netlink_sendmsg+0x8c3/0xcd0 net/netlink/af_netlink.c:1883
> sock_sendmsg_nosec net/socket.c:712 [inline]
> __sock_sendmsg+0x221/0x270 net/socket.c:727
> ____sys_sendmsg+0x523/0x860 net/socket.c:2566
> ___sys_sendmsg net/socket.c:2620 [inline]
> __sys_sendmsg+0x271/0x360 net/socket.c:2652
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f8427b614a9
> Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fff9b59f3a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007fff9b59f578 RCX: 00007f8427b614a9
> RDX: 0000000000000000 RSI: 0000200000000300 RDI: 0000000000000004
> RBP: 00007f8427bd4610 R08: 000000000000000c R09: 00007fff9b59f578
> R10: 000000000000001b R11: 0000000000000246 R12: 0000000000000001
> R13:
>
> Fixes: 4c975fd70002 ("net: hold instance lock during NETDEV_REGISTER/UP")
> Reported-by: syzbot+45016fe295243a7882d3@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=45016fe295243a7882d3
> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v1 net] rtnetlink: Fix bad unlock balance in do_setlink().
2025-04-07 16:42 [PATCH v1 net] rtnetlink: Fix bad unlock balance in do_setlink() Kuniyuki Iwashima
2025-04-07 16:57 ` Stanislav Fomichev
@ 2025-04-08 19:51 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2025-04-08 19:51 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: davem, edumazet, kuba, pabeni, horms, sdf, kuni1840, netdev,
syzbot+45016fe295243a7882d3
Hello:
This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Mon, 7 Apr 2025 09:42:22 -0700 you wrote:
> When validate_linkmsg() fails in do_setlink(), we jump to the errout
> label and calls netdev_unlock_ops() even though we have not called
> netdev_lock_ops() as reported by syzbot. [0]
>
> Let's return an error directly in such a case.
>
> [0]
> WARNING: bad unlock balance detected!
> 6.14.0-syzkaller-12504-g8bc251e5d874 #0 Not tainted
>
> [...]
Here is the summary with links:
- [v1,net] rtnetlink: Fix bad unlock balance in do_setlink().
https://git.kernel.org/netdev/net/c/445e99bdf68d
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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2025-04-07 16:42 [PATCH v1 net] rtnetlink: Fix bad unlock balance in do_setlink() Kuniyuki Iwashima
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2025-04-08 19:51 ` patchwork-bot+netdevbpf
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