From: syzbot <syzbot+b5ddc2aecb8d1b29c871@syzkaller.appspotmail.com>
To: davem@davemloft.net, edumazet@google.com, horms@kernel.org,
kuba@kernel.org, kuniyu@google.com,
linux-kernel@vger.kernel.org, luto@kernel.org,
ncardwell@google.com, netdev@vger.kernel.org, pabeni@redhat.com,
peterz@infradead.org, syzkaller-bugs@googlegroups.com,
tglx@kernel.org
Subject: Re: [syzbot] [net?] WARNING: locking bug in finish_task_switch (3)
Date: Fri, 18 Sep 2026 14:24:35 -0700 [thread overview]
Message-ID: <6aadac13.b398a7c9.1f86be.003c.GAE@google.com> (raw)
In-Reply-To: <6aa3307a.6e6c5f9e.28f11f.003a.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: 50d05c7c76c9 Merge tag 'landlock-7.3-rc3' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15b5f8c9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=b5ddc2aecb8d1b29c871
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12ab4525580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14d4e915580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/daf497619736/disk-50d05c7c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/748fbd82f647/vmlinux-50d05c7c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e61c59099d07/bzImage-50d05c7c.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b5ddc2aecb8d1b29c871@syzkaller.appspotmail.com
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: kernel/locking/lockdep.c:238 at hlock_class kernel/locking/lockdep.c:238 [inline], CPU#0: syz.1.28/6067
WARNING: kernel/locking/lockdep.c:238 at check_wait_context kernel/locking/lockdep.c:4923 [inline], CPU#0: syz.1.28/6067
WARNING: kernel/locking/lockdep.c:238 at __lock_acquire+0x5f0/0x2de0 kernel/locking/lockdep.c:5238, CPU#0: syz.1.28/6067
Modules linked in:
CPU: 0 UID: 0 PID: 6067 Comm: syz.1.28 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:hlock_class kernel/locking/lockdep.c:238 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4923 [inline]
RIP: 0010:__lock_acquire+0x5f7/0x2de0 kernel/locking/lockdep.c:5238
Code: 83 3d bc f2 fa 18 00 75 27 90 e8 94 e8 37 03 85 c0 74 1c 83 3d ed 29 d7 0e 00 75 13 48 8d 3d e0 32 da 0e 48 c7 c6 29 f3 59 8e <67> 48 0f b9 3a 90 31 c9 0f b6 81 c4 00 00 00 84 c0 0f 84 76 ff ff
RSP: 0000:ffffc90003a6e538 EFLAGS: 00010046
RAX: 0000000000000001 RBX: ffff88802f13e9b8 RCX: ffff88802f13ddc0
RDX: 0000000040000000 RSI: ffffffff8e59f329 RDI: ffffffff907d6580
RBP: ffff88802f13e9c0 R08: ffffffff907a5c83 R09: 1ffffffff20f4b90
R10: dffffc0000000000 R11: fffffbfff20f4b91 R12: 0000000000000004
R13: 0000000000000000 R14: ffff88802f13ddc0 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff888124cd2000(0063) knlGS:00000000f67c3b40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f71c8c10 CR3: 00000000711ba000 CR4: 00000000003526f0
Call Trace:
<TASK>
lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
finish_lock_switch kernel/sched/core.c:5254 [inline]
finish_task_switch+0x16e/0xc60 kernel/sched/core.c:5375
context_switch kernel/sched/core.c:5529 [inline]
__schedule+0x17e3/0x58f0 kernel/sched/core.c:7276
__schedule_loop kernel/sched/core.c:7353 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7368
__lock_sock+0x162/0x2c0 net/core/sock.c:3238
__lock_sock_fast+0x94/0xe0 net/core/sock.c:3900
lock_sock_fast include/net/sock.h:1746 [inline]
tcp_get_info+0x26d/0x2b70 net/ipv4/tcp.c:4250
inet_sk_diag_fill+0xdb6/0x18c0 net/ipv4/inet_diag.c:330
sk_diag_fill+0x2e6/0xd50 net/ipv4/tcp_diag.c:284
tcp_diag_dump+0x1ba6/0x2020 net/ipv4/tcp_diag.c:538
__inet_diag_dump net/ipv4/inet_diag.c:823 [inline]
inet_diag_dump_compat+0x274/0x490 net/ipv4/inet_diag.c:927
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]
inet_diag_rcv_msg_compat+0x214/0x420 net/ipv4/inet_diag.c:962
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+0x7bd/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:800
__sock_sendmsg net/socket.c:815 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2713
___sys_sendmsg+0x2a5/0x360 net/socket.c:2767
__sys_sendmsg+0x177/0x240 net/socket.c:2799
do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
__do_fast_syscall_32+0x27a/0x6a0 arch/x86/entry/syscall_32.c:291
do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:316
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf700f0ec
Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
RSP: 002b:00000000f67c350c EFLAGS: 00000206 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 0000000080000240
RDX: 0000000004004010 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
Code disassembly (best guess):
0: 83 3d bc f2 fa 18 00 cmpl $0x0,0x18faf2bc(%rip) # 0x18faf2c3
7: 75 27 jne 0x30
9: 90 nop
a: e8 94 e8 37 03 call 0x337e8a3
f: 85 c0 test %eax,%eax
11: 74 1c je 0x2f
13: 83 3d ed 29 d7 0e 00 cmpl $0x0,0xed729ed(%rip) # 0xed72a07
1a: 75 13 jne 0x2f
1c: 48 8d 3d e0 32 da 0e lea 0xeda32e0(%rip),%rdi # 0xeda3303
23: 48 c7 c6 29 f3 59 8e mov $0xffffffff8e59f329,%rsi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 90 nop
30: 31 c9 xor %ecx,%ecx
32: 0f b6 81 c4 00 00 00 movzbl 0xc4(%rcx),%eax
39: 84 c0 test %al,%al
3b: 0f .byte 0xf
3c: 84 76 ff test %dh,-0x1(%rsi)
3f: ff .byte 0xff
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
next prev parent reply other threads:[~2026-09-18 21:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-10 22:34 [syzbot] [kernel?] " syzbot
2026-09-18 21:24 ` syzbot [this message]
2026-09-18 22:51 ` [syzbot] [net?] " Hillf Danton
2026-09-19 6:56 ` syzbot
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