syzbot


inconsistent lock state in htab_map_delete_elem

Status: upstream: reported C repro on 2025/11/29 21:34
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+33a29bcf8af10436a5c7@syzkaller.appspotmail.com
First crash: 2d18h, last: 2d01h
Bug presence (2)
Date Name Commit Repro Result
2025/11/30 linux-5.15.y (ToT) cc5ec8769306 C [report] inconsistent lock state in htab_map_delete_elem
2025/11/30 upstream (ToT) 6bda50f4333f C Didn't crash

Sample crash report:
================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
syz.0.17/4355 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff8880798d61d0 (&htab->lockdep_key){....}-{2:2}, at: htab_lock_bucket kernel/bpf/hashtab.c:183 [inline]
ffff8880798d61d0 (&htab->lockdep_key){....}-{2:2}, at: htab_map_delete_elem+0x1b2/0x520 kernel/bpf/hashtab.c:1361
{INITIAL USE} state was registered at:
  lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
  _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
  htab_lock_bucket kernel/bpf/hashtab.c:183 [inline]
  htab_map_delete_elem+0x1b2/0x520 kernel/bpf/hashtab.c:1361
  bpf_prog_653fb3e4a9309dc2+0x42/0x5d0
  bpf_dispatcher_nop_func include/linux/bpf.h:888 [inline]
  __bpf_prog_run include/linux/filter.h:628 [inline]
  bpf_prog_run include/linux/filter.h:635 [inline]
  bpf_overflow_handler+0x1c4/0x4c0 kernel/events/core.c:10297
  __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
  perf_swevent_overflow kernel/events/core.c:9591 [inline]
  perf_swevent_event+0x4ad/0x530 kernel/events/core.c:9629
  perf_bp_event+0x224/0x290 kernel/events/core.c:10484
  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:83 [inline]
  atomic_notifier_call_chain+0x15d/0x280 kernel/notifier.c:198
  notify_die+0x12d/0x180 kernel/notifier.c:529
  notify_debug+0x20/0x30 arch/x86/kernel/traps.c:872
  exc_debug_user arch/x86/kernel/traps.c:998 [inline]
  noist_exc_debug+0x73/0x120 arch/x86/kernel/traps.c:1035
  asm_exc_debug+0x2f/0x40 arch/x86/include/asm/idtentry.h:642
irq event stamp: 2560
hardirqs last  enabled at (2559): [<ffffffff89a949f6>] exc_debug_kernel arch/x86/kernel/traps.c:947 [inline]
hardirqs last  enabled at (2559): [<ffffffff89a949f6>] exc_debug+0xe6/0x130 arch/x86/kernel/traps.c:1029
hardirqs last disabled at (2560): [<ffffffff89a9497e>] exc_debug_kernel arch/x86/kernel/traps.c:893 [inline]
hardirqs last disabled at (2560): [<ffffffff89a9497e>] exc_debug+0x6e/0x130 arch/x86/kernel/traps.c:1029
softirqs last  enabled at (2288): [<ffffffff81856560>] bpf_prog_load+0x1150/0x1550 kernel/bpf/syscall.c:2380
softirqs last disabled at (2286): [<ffffffff8183c969>] spin_lock_bh include/linux/spinlock.h:369 [inline]
softirqs last disabled at (2286): [<ffffffff8183c969>] bpf_ksym_add+0x29/0x340 kernel/bpf/core.c:633

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.0.17/4355.

stack backtrace:
CPU: 1 PID: 4355 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+0x168/0x230 lib/dump_stack.c:106
 lock_acquire+0x2b2/0x3f0 kernel/locking/lockdep.c:5614
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
 htab_lock_bucket kernel/bpf/hashtab.c:183 [inline]
 htab_map_delete_elem+0x1b2/0x520 kernel/bpf/hashtab.c:1361
 bpf_prog_653fb3e4a9309dc2+0x42/0x5d0
 bpf_dispatcher_nop_func include/linux/bpf.h:888 [inline]
 __bpf_prog_run include/linux/filter.h:628 [inline]
 bpf_prog_run include/linux/filter.h:635 [inline]
 bpf_overflow_handler+0x1c4/0x4c0 kernel/events/core.c:10297
 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
 perf_swevent_overflow kernel/events/core.c:9591 [inline]
 perf_swevent_event+0x4ad/0x530 kernel/events/core.c:9629
 perf_bp_event+0x224/0x290 kernel/events/core.c:10484
 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:83 [inline]
 atomic_notifier_call_chain+0x15d/0x280 kernel/notifier.c:198
 notify_die+0x12d/0x180 kernel/notifier.c:529
 notify_debug+0x20/0x30 arch/x86/kernel/traps.c:872
 exc_debug_kernel arch/x86/kernel/traps.c:929 [inline]
 exc_debug+0xcf/0x130 arch/x86/kernel/traps.c:1029
 asm_exc_debug+0x1a/0x40 arch/x86/include/asm/idtentry.h:642
RIP: 0010:copy_user_generic_unrolled+0xa2/0xc0 arch/x86/lib/copy_user_64.S:102
Code: ff c9 75 b6 89 d1 83 e2 07 c1 e9 03 74 12 4c 8b 06 4c 89 07 48 8d 76 08 48 8d 7f 08 ff c9 75 ee 21 d2 74 10 89 d1 8a 06 88 07 <48> ff c6 48 ff c7 ff c9 75 f2 31 c0 0f 01 ca c3 90 90 90 90 90 90
RSP: 0018:ffffc9000333f0f8 EFLAGS: 00040202
RAX: ffffffff83daee20 RBX: 0000000000000004 RCX: 0000000000000002
RDX: 0000000000000004 RSI: ffff88807ccb466e RDI: 0000200000000302
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed100f9968ce
R10: ffffed100f9968ce R11: 1ffff1100f9968cd R12: 00007ffffffff000
R13: 0000200000000304 R14: ffff88807ccb466c R15: 0000200000000300
 </#DB>
 <TASK>
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline]
 _copy_to_user+0xf0/0x130 lib/usercopy.c:40
 copy_to_user include/linux/uaccess.h:200 [inline]
 bpf_verifier_vlog+0x1b5/0x350 kernel/bpf/verifier.c:303
 verbose+0x1dc/0x2a0 kernel/bpf/verifier.c:348
 do_check+0x4785/0xeac0 kernel/bpf/verifier.c:11266
 do_check_common+0xe67/0x16c0 kernel/bpf/verifier.c:13506
 do_check_main kernel/bpf/verifier.c:13569 [inline]
 bpf_check+0x31f3/0xf090 kernel/bpf/verifier.c:14140
 bpf_prog_load+0x1043/0x1550 kernel/bpf/syscall.c:2354
 __sys_bpf+0x4c2/0x670 kernel/bpf/syscall.c:4657
 __do_sys_bpf kernel/bpf/syscall.c:4761 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4759 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f32fa1ce749
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:00007fffdab375e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f32fa424fa0 RCX: 00007f32fa1ce749
RDX: 0000000000000048 RSI: 0000200000000240 RDI: 0000000000000005
RBP: 00007f32fa252f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f32fa424fa0 R14: 00007f32fa424fa0 R15: 0000000000000003
 </TASK>
----------------
Code disassembly (best guess):
   0:	ff c9                	dec    %ecx
   2:	75 b6                	jne    0xffffffba
   4:	89 d1                	mov    %edx,%ecx
   6:	83 e2 07             	and    $0x7,%edx
   9:	c1 e9 03             	shr    $0x3,%ecx
   c:	74 12                	je     0x20
   e:	4c 8b 06             	mov    (%rsi),%r8
  11:	4c 89 07             	mov    %r8,(%rdi)
  14:	48 8d 76 08          	lea    0x8(%rsi),%rsi
  18:	48 8d 7f 08          	lea    0x8(%rdi),%rdi
  1c:	ff c9                	dec    %ecx
  1e:	75 ee                	jne    0xe
  20:	21 d2                	and    %edx,%edx
  22:	74 10                	je     0x34
  24:	89 d1                	mov    %edx,%ecx
  26:	8a 06                	mov    (%rsi),%al
  28:	88 07                	mov    %al,(%rdi)
* 2a:	48 ff c6             	inc    %rsi <-- trapping instruction
  2d:	48 ff c7             	inc    %rdi
  30:	ff c9                	dec    %ecx
  32:	75 f2                	jne    0x26
  34:	31 c0                	xor    %eax,%eax
  36:	0f 01 ca             	clac
  39:	c3                   	ret
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/29 21:33 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf inconsistent lock state in htab_map_delete_elem
* Struck through repros no longer work on HEAD.