syzbot


inconsistent lock state in htab_lock_bucket

Status: upstream: reported C repro on 2025/11/30 04:04
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+0057e0c996f6b53410fd@syzkaller.appspotmail.com
First crash: 2d12h, last: 13h38m
Bug presence (2)
Date Name Commit Repro Result
2025/11/30 linux-6.6.y (ToT) 1e89a1be4fe9 C [report] inconsistent lock state in htab_lock_bucket
2025/11/30 upstream (ToT) 6bda50f4333f C Didn't crash
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 inconsistent lock state in htab_lock_bucket origin:lts-only 4 C 2 13h06m 2d16h 0/3 upstream: reported C repro on 2025/11/29 23:34

Sample crash report:
================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
syz.0.340/6278 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff88801cb00218 (&htab->lockdep_key#3){....}-{2:2}, at: htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166
{INITIAL USE} state was registered at:
  lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
  _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
  htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166
  htab_lru_map_delete_elem+0x1a4/0x630 kernel/bpf/hashtab.c:1479
  bpf_prog_2c29ac5cdc6b1842+0x42/0x46
  bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
  __bpf_prog_run include/linux/filter.h:612 [inline]
  bpf_prog_run include/linux/filter.h:619 [inline]
  bpf_overflow_handler+0x1f9/0x4f0 kernel/events/core.c:10547
  __perf_event_overflow+0x447/0x630 kernel/events/core.c:9718
  perf_swevent_overflow kernel/events/core.c:9794 [inline]
  perf_swevent_event+0x4de/0x5c0 kernel/events/core.c:9832
  perf_bp_event+0x252/0x300 kernel/events/core.c:10739
  hw_breakpoint_handler arch/x86/kernel/hw_breakpoint.c:555 [inline]
  hw_breakpoint_exceptions_notify+0x23e/0x670 arch/x86/kernel/hw_breakpoint.c:586
  notifier_call_chain+0x197/0x390 kernel/notifier.c:93
  atomic_notifier_call_chain+0xda/0x180 kernel/notifier.c:231
  notify_die+0x131/0x180 kernel/notifier.c:596
  notify_debug+0x2e/0x50 arch/x86/kernel/traps.c:1042
  exc_debug_user arch/x86/kernel/traps.c:1168 [inline]
  noist_exc_debug+0x77/0x120 arch/x86/kernel/traps.c:1205
  asm_exc_debug+0x33/0x40 arch/x86/include/asm/idtentry.h:644
irq event stamp: 1994
hardirqs last  enabled at (1993): [<ffffffff8a6eebfd>] exc_debug_kernel arch/x86/kernel/traps.c:1117 [inline]
hardirqs last  enabled at (1993): [<ffffffff8a6eebfd>] exc_debug+0xfd/0x140 arch/x86/kernel/traps.c:1199
hardirqs last disabled at (1994): [<ffffffff8a6eeb7b>] exc_debug_kernel arch/x86/kernel/traps.c:1063 [inline]
hardirqs last disabled at (1994): [<ffffffff8a6eeb7b>] exc_debug+0x7b/0x140 arch/x86/kernel/traps.c:1199
softirqs last  enabled at (1694): [<ffffffff8194a352>] bpf_prog_load+0x12f2/0x16d0 kernel/bpf/syscall.c:2776
softirqs last disabled at (1692): [<ffffffff8192b10d>] spin_lock_bh include/linux/spinlock.h:356 [inline]
softirqs last disabled at (1692): [<ffffffff8192b10d>] bpf_ksym_add+0x2d/0x340 kernel/bpf/core.c:655

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

       CPU0
       ----
  lock(&htab->lockdep_key#3);
  <Interrupt>
    lock(&htab->lockdep_key#3);

 *** DEADLOCK ***

no locks held by syz.0.340/6278.

stack backtrace:
CPU: 0 PID: 6278 Comm: syz.0.340 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <#DB>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 lock_acquire+0x2b1/0x410 kernel/locking/lockdep.c:5745
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166
 htab_lru_map_delete_elem+0x1a4/0x630 kernel/bpf/hashtab.c:1479
 bpf_prog_2c29ac5cdc6b1842+0x42/0x46
 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
 __bpf_prog_run include/linux/filter.h:612 [inline]
 bpf_prog_run include/linux/filter.h:619 [inline]
 bpf_overflow_handler+0x1f9/0x4f0 kernel/events/core.c:10547
 __perf_event_overflow+0x447/0x630 kernel/events/core.c:9718
 perf_swevent_overflow kernel/events/core.c:9794 [inline]
 perf_swevent_event+0x4de/0x5c0 kernel/events/core.c:9832
 perf_bp_event+0x252/0x300 kernel/events/core.c:10739
 hw_breakpoint_handler arch/x86/kernel/hw_breakpoint.c:555 [inline]
 hw_breakpoint_exceptions_notify+0x23e/0x670 arch/x86/kernel/hw_breakpoint.c:586
 notifier_call_chain+0x197/0x390 kernel/notifier.c:93
 atomic_notifier_call_chain+0xda/0x180 kernel/notifier.c:231
 notify_die+0x131/0x180 kernel/notifier.c:596
 notify_debug+0x2e/0x50 arch/x86/kernel/traps.c:1042
 exc_debug_kernel arch/x86/kernel/traps.c:1099 [inline]
 exc_debug+0xe6/0x140 arch/x86/kernel/traps.c:1199
 asm_exc_debug+0x1e/0x40 arch/x86/include/asm/idtentry.h:644
RIP: 0010:rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:71
Code: 75 f1 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08 73 e8 eb c9 <f3> a4 c3 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48 29 f8 48 01
RSP: 0018:ffffc9000c54fb48 EFLAGS: 00050202
RAX: ffffffff841f3d01 RBX: 0000000000000078 RCX: 0000000000000036
RDX: 0000000000000001 RSI: 0000200000000302 RDI: ffffc9000320408a
RBP: 0000000000000000 R08: ffffc900032040bf R09: 1ffff92000640817
R10: dffffc0000000000 R11: fffff52000640818 R12: 0000200000000338
R13: ffffc9000c54fdc8 R14: ffffc90003204048 R15: 00002000000002c0
 </#DB>
 <TASK>
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:127 [inline]
 _copy_from_user+0x8b/0xe0 lib/usercopy.c:23
 copy_from_user include/linux/uaccess.h:183 [inline]
 copy_from_bpfptr_offset include/linux/bpfptr.h:53 [inline]
 copy_from_bpfptr+0x67/0x80 include/linux/bpfptr.h:59
 bpf_prog_load+0xa64/0x16d0 kernel/bpf/syscall.c:2706
 __sys_bpf+0x55a/0x800 kernel/bpf/syscall.c:5473
 __do_sys_bpf kernel/bpf/syscall.c:5577 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5575 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5575
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7833b8f749
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:00007fffe7847db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f7833de5fa0 RCX: 00007f7833b8f749
RDX: 0000000000000094 RSI: 00002000000007c0 RDI: 0000000000000005
RBP: 00007f7833c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7833de5fa0 R14: 00007f7833de5fa0 R15: 0000000000000003
 </TASK>
----------------
Code disassembly (best guess):
   0:	75 f1                	jne    0xfffffff3
   2:	c3                   	ret
   3:	66 2e 0f 1f 84 00 00 	cs nopw 0x0(%rax,%rax,1)
   a:	00 00 00
   d:	0f 1f 00             	nopl   (%rax)
  10:	48 8b 06             	mov    (%rsi),%rax
  13:	48 89 07             	mov    %rax,(%rdi)
  16:	48 83 c6 08          	add    $0x8,%rsi
  1a:	48 83 c7 08          	add    $0x8,%rdi
  1e:	83 e9 08             	sub    $0x8,%ecx
  21:	74 df                	je     0x2
  23:	83 f9 08             	cmp    $0x8,%ecx
  26:	73 e8                	jae    0x10
  28:	eb c9                	jmp    0xfffffff3
* 2a:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction
  2c:	c3                   	ret
  2d:	48 8b 06             	mov    (%rsi),%rax
  30:	48 89 07             	mov    %rax,(%rdi)
  33:	48 8d 47 08          	lea    0x8(%rdi),%rax
  37:	48 83 e0 f8          	and    $0xfffffffffffffff8,%rax
  3b:	48 29 f8             	sub    %rdi,%rax
  3e:	48                   	rex.W
  3f:	01                   	.byte 0x1

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/02 02:45 linux-6.6.y 4791134e4aeb d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf inconsistent lock state in htab_lock_bucket
2025/11/30 04:04 linux-6.6.y 1e89a1be4fe9 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf inconsistent lock state in htab_lock_bucket
* Struck through repros no longer work on HEAD.