syzbot


inconsistent lock state in htab_lock_bucket

Status: upstream: reported C repro on 2025/11/29 23:34
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+743d77affd179ca0ad40@syzkaller.appspotmail.com
First crash: 2d16h, last: 12h19m
Bug presence (2)
Date Name Commit Repro Result
2025/11/30 linux-6.1.y (ToT) f6e38ae624cf C [report] inconsistent lock state in htab_lock_bucket
2025/11/30 upstream (ToT) e69c7c175115 C Didn't crash
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 inconsistent lock state in htab_lock_bucket origin:lts-only 4 C 2 12h51m 2d11h 0/2 upstream: reported C repro on 2025/11/30 04:04

Sample crash report:
================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
syz.0.17/4426 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff888078b3f820 (&htab->lockdep_key){....}-{2:2}, at: htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166
{INITIAL USE} state was registered at:
  lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
  _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
  htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166
  htab_lru_map_delete_elem+0x1ad/0x760 kernel/bpf/hashtab.c:1438
  bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
  bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
  __bpf_prog_run include/linux/filter.h:603 [inline]
  bpf_prog_run include/linux/filter.h:610 [inline]
  bpf_overflow_handler+0x525/0x7b0 kernel/events/core.c:10286
  __perf_event_overflow+0x448/0x610 kernel/events/core.c:9496
  perf_swevent_overflow kernel/events/core.c:9572 [inline]
  perf_swevent_event+0x4ad/0x530 kernel/events/core.c:9610
  perf_bp_event+0x23a/0x2a0 kernel/events/core.c:10478
  hw_breakpoint_handler arch/x86/kernel/hw_breakpoint.c:555 [inline]
  hw_breakpoint_exceptions_notify+0x152/0x470 arch/x86/kernel/hw_breakpoint.c:586
  notifier_call_chain kernel/notifier.c:87 [inline]
  atomic_notifier_call_chain+0x17a/0x2b0 kernel/notifier.c:225
  notify_die+0x12d/0x180 kernel/notifier.c:593
  notify_debug+0x20/0x30 arch/x86/kernel/traps.c:1018
  exc_debug_user arch/x86/kernel/traps.c:1144 [inline]
  noist_exc_debug+0x73/0x120 arch/x86/kernel/traps.c:1181
  asm_exc_debug+0x2f/0x40 arch/x86/include/asm/idtentry.h:648
irq event stamp: 2248
hardirqs last  enabled at (2247): [<ffffffff8a17a5c0>] exc_debug_kernel arch/x86/kernel/traps.c:1093 [inline]
hardirqs last  enabled at (2247): [<ffffffff8a17a5c0>] exc_debug+0xf0/0x130 arch/x86/kernel/traps.c:1175
hardirqs last disabled at (2248): [<ffffffff8a17a53e>] exc_debug_kernel arch/x86/kernel/traps.c:1039 [inline]
hardirqs last disabled at (2248): [<ffffffff8a17a53e>] exc_debug+0x6e/0x130 arch/x86/kernel/traps.c:1175
softirqs last  enabled at (1894): [<ffffffff818f072f>] bpf_prog_load+0x117f/0x15a0 kernel/bpf/syscall.c:2674
softirqs last disabled at (1892): [<ffffffff818d4a79>] spin_lock_bh include/linux/spinlock.h:356 [inline]
softirqs last disabled at (1892): [<ffffffff818d4a79>] bpf_ksym_add+0x29/0x340 kernel/bpf/core.c:649

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&htab->lockdep_key);
  <Interrupt>
    lock(&htab->lockdep_key);

 *** DEADLOCK ***

no locks held by syz.0.17/4426.

stack backtrace:
CPU: 1 PID: 4426 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <#DB>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 lock_acquire+0x2ce/0x490 kernel/locking/lockdep.c:5653
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 htab_lock_bucket+0x17d/0x300 kernel/bpf/hashtab.c:166
 htab_lru_map_delete_elem+0x1ad/0x760 kernel/bpf/hashtab.c:1438
 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 bpf_overflow_handler+0x525/0x7b0 kernel/events/core.c:10286
 __perf_event_overflow+0x448/0x610 kernel/events/core.c:9496
 perf_swevent_overflow kernel/events/core.c:9572 [inline]
 perf_swevent_event+0x4ad/0x530 kernel/events/core.c:9610
 perf_bp_event+0x23a/0x2a0 kernel/events/core.c:10478
 hw_breakpoint_handler arch/x86/kernel/hw_breakpoint.c:555 [inline]
 hw_breakpoint_exceptions_notify+0x152/0x470 arch/x86/kernel/hw_breakpoint.c:586
 notifier_call_chain kernel/notifier.c:87 [inline]
 atomic_notifier_call_chain+0x17a/0x2b0 kernel/notifier.c:225
 notify_die+0x12d/0x180 kernel/notifier.c:593
 notify_debug+0x20/0x30 arch/x86/kernel/traps.c:1018
 exc_debug_kernel arch/x86/kernel/traps.c:1075 [inline]
 exc_debug+0xd9/0x130 arch/x86/kernel/traps.c:1175
 asm_exc_debug+0x1a/0x40 arch/x86/include/asm/idtentry.h:648
RIP: 0010:copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:166
Code: ff c9 75 f2 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 20 0f 01 cb 83 fa 40 72 38 89 d1 <f3> a4 31 c0 0f 01 ca c3 89 ca eb 0a 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90003407b40 EFLAGS: 00050202
RAX: ffffffff84072901 RBX: 0000000000000078 RCX: 0000000000000036
RDX: 0000000000000078 RSI: 0000200000000302 RDI: ffffc9000256b08a
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff520004ad618
R10: fffff520004ad618 R11: 1ffff920004ad609 R12: 00007fffffffef88
R13: 1ffff92000680f84 R14: ffffc9000256b048 R15: 00002000000002c0
 </#DB>
 <TASK>
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline]
 _copy_from_user+0xf4/0x170 lib/usercopy.c:23
 copy_from_user include/linux/uaccess.h:161 [inline]
 copy_from_bpfptr_offset include/linux/bpfptr.h:53 [inline]
 copy_from_bpfptr+0x67/0x80 include/linux/bpfptr.h:59
 bpf_prog_load+0xb4b/0x15a0 kernel/bpf/syscall.c:2619
 __sys_bpf+0x520/0x6d0 kernel/bpf/syscall.c:5027
 __do_sys_bpf kernel/bpf/syscall.c:5131 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5129 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc9a858f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcb4c1fc88 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fc9a87e5fa0 RCX: 00007fc9a858f749
RDX: 0000000000000094 RSI: 00002000000007c0 RDI: 0000000000000005
RBP: 00007fc9a8613f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc9a87e5fa0 R14: 00007fc9a87e5fa0 R15: 0000000000000003
 </TASK>
----------------
Code disassembly (best guess):
   0:	ff c9                	dec    %ecx
   2:	75 f2                	jne    0xfffffff6
   4:	89 d1                	mov    %edx,%ecx
   6:	c1 e9 03             	shr    $0x3,%ecx
   9:	83 e2 07             	and    $0x7,%edx
   c:	f3 48 a5             	rep movsq %ds:(%rsi),%es:(%rdi)
   f:	89 d1                	mov    %edx,%ecx
  11:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi)
  13:	31 c0                	xor    %eax,%eax
  15:	0f 01 ca             	clac
  18:	c3                   	ret
  19:	8d 0c ca             	lea    (%rdx,%rcx,8),%ecx
  1c:	89 ca                	mov    %ecx,%edx
  1e:	eb 20                	jmp    0x40
  20:	0f 01 cb             	stac
  23:	83 fa 40             	cmp    $0x40,%edx
  26:	72 38                	jb     0x60
  28:	89 d1                	mov    %edx,%ecx
* 2a:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction
  2c:	31 c0                	xor    %eax,%eax
  2e:	0f 01 ca             	clac
  31:	c3                   	ret
  32:	89 ca                	mov    %ecx,%edx
  34:	eb 0a                	jmp    0x40
  36:	90                   	nop
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/02 03:16 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf inconsistent lock state in htab_lock_bucket
2025/11/29 23:33 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf inconsistent lock state in htab_lock_bucket
* Struck through repros no longer work on HEAD.