Re: [syzbot ci] Re: net/smc: fix clcsock and lgr/lnk races in smc_diag dump path

[Mahanta Jambigi <mjambigi@linux.ibm.com>]

On 07/08/26 8:32 pm, syzbot ci wrote:
> syzbot ci has tested the following series
> 
> [v3] net/smc: fix clcsock and lgr/lnk races in smc_diag dump path
> https://lore.kernel.org/all/20260807081606.3200128-1-mjambigi@linux.ibm.com
> * [PATCH net v3] net/smc: fix clcsock and lgr/lnk races in smc_diag dump path
> 
> and found the following issue:
> WARNING in smc_diag_dump_proto
> 
> Full report is available here:
> https://ci.syzbot.org/series/ab0d12fd-741a-4a0f-9f49-e52b84e94f4a
> 
> ***
> 
> WARNING in smc_diag_dump_proto
> 
> tree:      net
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net.git
> base:      594d905195024b228c962627ae5ae7c17bd582a4
> arch:      amd64
> compiler:  Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> config:    https://ci.syzbot.org/builds/0c4d246f-d098-4afe-b6bc-0f0ad52f55f8/config
> syz repro: https://ci.syzbot.org/findings/fa5564b8-8db6-4f76-9d75-dbd796435d87/syz_repro
> 
> ------------[ cut here ]------------
> DEBUG_LOCKS_WARN_ON(lock->magic != lock)
> WARNING: kernel/locking/mutex.c:625 at __mutex_lock_common kernel/locking/mutex.c:625 [inline], CPU#0: syz.0.161/6326
> WARNING: kernel/locking/mutex.c:625 at __mutex_lock+0x12d8/0x1550 kernel/locking/mutex.c:821, CPU#0: syz.0.161/6326

I have fixed this syzbot issue by submitting a separate fix. I also
tested the fix by submitting the patch to syzbot & after that this issue
is not seen anymore. One can see the test details with a fixed patch in
below link. I'll send that patch separately to netdev shortly.

https://ci.syzbot.org/series/ab0d12fd-741a-4a0f-9f49-e52b84e94f4a

> Modules linked in:
> CPU: 0 UID: 0 PID: 6326 Comm: syz.0.161 Not tainted syzkaller #0 PREEMPT(full) 
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:625 [inline]
> RIP: 0010:__mutex_lock+0x12df/0x1550 kernel/locking/mutex.c:821
> Code: de 57 90 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 47 02 00 00 83 3d 45 cc 83 04 00 75 13 48 8d 3d a8 1b 87 04 48 c7 c6 40 f7 ec 8b <67> 48 0f b9 3a 90 e9 75 ee ff ff 90 0f 0b 90 e9 48 f2 ff ff 90 0f
> RSP: 0018:ffffc900068c6e40 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff888170ffd940
> RDX: 0000000000000000 RSI: ffffffff8becf740 RDI: ffffffff905b2db0
> RBP: ffffc900068c6fd0 R08: ffffffff9057de43 R09: 1ffffffff20afbc8
> R10: dffffc0000000000 R11: fffffbfff20afbc9 R12: ffff8881b1006648
> R13: 0000000000000000 R14: 1ffff92000d18ddc R15: 0000000000000000
> FS:  00007f4dacd826c0(0000) GS:ffff88818d945000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000020000000e000 CR3: 0000000171350000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  smc_diag_msg_common_fill net/smc/smc_diag.c:50 [inline]
>  __smc_diag_dump net/smc/smc_diag.c:101 [inline]
>  smc_diag_dump_proto+0x6d2/0x2620 net/smc/smc_diag.c:255
>  smc_diag_dump+0x59/0xa0 net/smc/smc_diag.c:278
>  netlink_dump+0x711/0xee0 net/netlink/af_netlink.c:2331
>  __netlink_dump_start+0x589/0x7b0 net/netlink/af_netlink.c:2446
>  netlink_dump_start include/linux/netlink.h:341 [inline]
>  smc_diag_handler_dump+0x199/0x240 net/smc/smc_diag.c:293
>  sock_diag_rcv_msg+0x4b0/0x5f0 net/core/sock_diag.c:-1
>  netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
>  netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
>  netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
>  netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
>  sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
>  __sock_sendmsg net/socket.c:790 [inline]
>  ____sys_sendmsg+0x54e/0x850 net/socket.c:2684
>  ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
>  __sys_sendmsg net/socket.c:2770 [inline]
>  __do_sys_sendmsg net/socket.c:2775 [inline]
>  __se_sys_sendmsg net/socket.c:2773 [inline]
>  __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f4dabf9e019
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f4dacd82028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007f4dac226090 RCX: 00007f4dabf9e019
> RDX: 0000000000000600 RSI: 0000200000000540 RDI: 0000000000000003
> RBP: 00007f4dac03500c R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f4dac226128 R14: 00007f4dac226090 R15: 00007ffe0de8ec98