Message-ID: <694995bf.050a0220.2fb209.01a1.GAE@google.com>
Date: Mon, 22 Dec 2025 11:02:23 -0800
From: syzbot <syzbot+c69a0a2c816716f1e0d5@...kaller.appspotmail.com>
To: andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org, 
	daniel@...earbox.net, eddyz87@...il.com, haoluo@...gle.com, 
	john.fastabend@...il.com, jolsa@...nel.org, kpsingh@...nel.org, 
	linux-kernel@...r.kernel.org, martin.lau@...ux.dev, netdev@...r.kernel.org, 
	sdf@...ichev.me, song@...nel.org, syzkaller-bugs@...glegroups.com, 
	yonghong.song@...ux.dev
Subject: [syzbot] [bpf?] inconsistent lock state in bpf_lru_push_free

Hello,

syzbot found the following issue on:

HEAD commit:    f785a31395d9 bpf: arm64: Fix sparse warnings
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1122d392580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a4aa52bacc0658d1
dashboard link: https://syzkaller.appspot.com/bug?extid=c69a0a2c816716f1e0d5
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1780f584580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7e044cc52f4d/disk-f785a313.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5af05af9fe6f/vmlinux-f785a313.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e8bd1bb41f24/bzImage-f785a313.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c69a0a2c816716f1e0d5@...kaller.appspotmail.com

================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
syz.0.17/5989 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffffe8ffffc2f8d8 (&l->lock#2){....}-{2:2}, at: bpf_lru_push_free+0x13e/0x520 kernel/bpf/bpf_lru_list.c:-1
{INITIAL USE} state was registered at:
  lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
  _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
  bpf_percpu_lru_pop_free kernel/bpf/bpf_lru_list.c:407 [inline]
  bpf_lru_pop_free+0xcb/0x19b0 kernel/bpf/bpf_lru_list.c:494
  prealloc_lru_pop kernel/bpf/hashtab.c:299 [inline]
  htab_lru_map_update_elem+0x168/0x8a0 kernel/bpf/hashtab.c:1215
  bpf_map_update_value+0x751/0x920 kernel/bpf/syscall.c:294
  generic_map_update_batch+0x5a9/0x810 kernel/bpf/syscall.c:2038
  bpf_map_do_batch+0x39b/0x630 kernel/bpf/syscall.c:5647
  __sys_bpf+0x750/0x8a0 kernel/bpf/syscall.c:-1
  __do_sys_bpf kernel/bpf/syscall.c:6320 [inline]
  __se_sys_bpf kernel/bpf/syscall.c:6318 [inline]
  __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6318
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
irq event stamp: 19654
hardirqs last  enabled at (19653): [<ffffffff8b5b413e>] syscall_enter_from_user_mode include/linux/entry-common.h:108 [inline]
hardirqs last  enabled at (19653): [<ffffffff8b5b413e>] do_syscall_64+0xbe/0xf80 arch/x86/entry/syscall_64.c:90
hardirqs last disabled at (19654): [<ffffffff8b5b8058>] exc_debug_kernel+0x68/0x150 arch/x86/kernel/traps.c:1233
softirqs last  enabled at (19590): [<ffffffff81d3246b>] bpf_prog_load+0x14fb/0x1a10 kernel/bpf/syscall.c:3118
softirqs last disabled at (19588): [<ffffffff81d0e0bd>] spin_lock_bh include/linux/spinlock.h:356 [inline]
softirqs last disabled at (19588): [<ffffffff81d0e0bd>] bpf_ksym_add+0x2d/0x340 kernel/bpf/core.c:640

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

       CPU0
       ----
  lock(&l->lock#2);
  <Interrupt>
    lock(&l->lock#2);

 *** DEADLOCK ***

no locks held by syz.0.17/5989.

stack backtrace:
CPU: 0 UID: 0 PID: 5989 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <#DB>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_usage_bug+0x28b/0x2e0 kernel/locking/lockdep.c:4042
 lock_acquire+0x1f8/0x340 kernel/locking/lockdep.c:5859
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
 bpf_lru_push_free+0x13e/0x520 kernel/bpf/bpf_lru_list.c:-1
 htab_lru_push_free kernel/bpf/hashtab.c:1183 [inline]
 htab_lru_map_delete_elem+0x3a3/0x410 kernel/bpf/hashtab.c:1464
 bpf_prog_464bc2be3fc7c272+0x43/0x4b
 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 bpf_overflow_handler kernel/events/core.c:10303 [inline]
 __perf_event_overflow+0x39c/0xe70 kernel/events/core.c:10402
 perf_swevent_overflow kernel/events/core.c:10536 [inline]
 perf_swevent_event+0x4f8/0x5e0 kernel/events/core.c:10574
 perf_bp_event+0x251/0x300 kernel/events/core.c:11395
 hw_breakpoint_handler arch/x86/kernel/hw_breakpoint.c:556 [inline]
 hw_breakpoint_exceptions_notify+0x244/0x680 arch/x86/kernel/hw_breakpoint.c:587
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 atomic_notifier_call_chain+0xda/0x180 kernel/notifier.c:223
 notify_die+0x130/0x180 kernel/notifier.c:588
 notify_debug+0x2e/0x50 arch/x86/kernel/traps.c:1208
 exc_debug_kernel+0xbe/0x150 arch/x86/kernel/traps.c:1270
 asm_exc_debug+0x1e/0x40 arch/x86/include/asm/idtentry.h:654
RIP: 0010:rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:74
Code: 48 04 00 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 db 83 f9 08 73 e8 eb c5 <f3> a4 e9 8f 48 04 00 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48
RSP: 0018:ffffc90003697cf8 EFLAGS: 00050202
RAX: 00007ffffffff001 RBX: 0000000000000050 RCX: 000000000000000f
RDX: 0000000000000001 RSI: 0000200000000301 RDI: ffffc90003697da1
RBP: ffffc90003697ea8 R08: ffffc90003697daf R09: 1ffff920006d2fb5
R10: dffffc0000000000 R11: fffff520006d2fb6 R12: ffffc90003697d60
R13: 0000000000000050 R14: ffffc90003697d60 R15: 00002000000002c0
 </#DB>
 <TASK>
 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline]
 _inline_copy_from_user include/linux/uaccess.h:185 [inline]
 _copy_from_user+0x7a/0xb0 lib/usercopy.c:18
 copy_from_user include/linux/uaccess.h:223 [inline]
 copy_from_bpfptr_offset include/linux/bpfptr.h:53 [inline]
 copy_from_bpfptr include/linux/bpfptr.h:59 [inline]
 __sys_bpf+0x1f2/0x8a0 kernel/bpf/syscall.c:6180
 __do_sys_bpf kernel/bpf/syscall.c:6320 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6318 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6318
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efcc198f749
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:00007efcc2754038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007efcc1be5fa0 RCX: 00007efcc198f749
RDX: 0000000000000050 RSI: 00002000000002c0 RDI: 000000000000000a
RBP: 00007efcc1a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efcc1be6038 R14: 00007efcc1be5fa0 R15: 00007ffd9db831a8
 </TASK>
----------------
Code disassembly (best guess):
   0:	48 04 00             	rex.W add $0x0,%al
   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 db                	je     0xfffffffe
  23:	83 f9 08             	cmp    $0x8,%ecx
  26:	73 e8                	jae    0x10
  28:	eb c5                	jmp    0xffffffef
* 2a:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction
  2c:	e9 8f 48 04 00       	jmp    0x448c0
  31:	48 8b 06             	mov    (%rsi),%rax
  34:	48 89 07             	mov    %rax,(%rdi)
  37:	48 8d 47 08          	lea    0x8(%rdi),%rax
  3b:	48 83 e0 f8          	and    $0xfffffffffffffff8,%rax
  3f:	48                   	rex.W


---
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