------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: sed/25041
Modules linked in:
CPU: 0 UID: 0 PID: 25041 Comm: sed Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: a4 fe 8e 0b 67 48 0f b9 3a eb 4a e8 b8 21 f3 fc 48 8d 3d a1 fe 8e 0b 67 48 0f b9 3a eb 37 e8 a5 21 f3 fc 48 8d 3d 9e fe 8e 0b <67> 48 0f b9 3a eb 24 e8 92 21 f3 fc 48 8d 3d 9b fe 8e 0b 67 48 0f
RSP: 0018:ffffc90000007c68 EFLAGS: 00010246
RAX: ffffffff84d3f2cb RBX: 0000000000000003 RCX: ffff88802bd08000
RDX: 0000000000000100 RSI: ffffffff8f3652c0 RDI: ffffffff9062f170
RBP: ffffc90000007d70 R08: ffff88802bd08000 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000100 R12: 0000000000000000
R13: 000000010001de08 R14: ffff888052346820 R15: ffff8880523469b8
FS: 0000000000000000(0000) GS:ffff888124f4d000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f69ef1dfe9c CR3: 000000007731a000 CR4: 0000000000350ef0
Call Trace:
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
handle_softirqs+0x225/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 f1 de 2e 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 db 69 ca 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 ab 7a 6d ff cc 48 8d 3d c8 61 b8
RSP: 0018:ffffc900030df510 EFLAGS: 00000282
RAX: adfc9c0d6f418100 RBX: 0000000000000000 RCX: 0000000080000002
RDX: 00000000706121d3 RSI: ffffffff8e4b3351 RDI: ffffffff8c4bdd80
RBP: ffffffff82260fbd R08: ffffffff82260fbd R09: 0000000000000000
R10: 0000000000008000 R11: ffff8880b8641098 R12: 0000000000000000
R13: ffff8880b8641098 R14: 0000000000000001 R15: 0000000000000246
__raw_spin_trylock include/linux/spinlock_api_smp.h:91 [inline]
_raw_spin_trylock+0x47/0x80 kernel/locking/spinlock.c:142
spin_trylock include/linux/spinlock.h:354 [inline]
free_unref_folios+0x109d/0x14a0 mm/page_alloc.c:3062
folios_put_refs+0x9e9/0xb30 mm/swap.c:1057
free_pages_and_swap_cache+0x2ba/0x490 mm/swap_state.c:586
__tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline]
tlb_batch_pages_flush mm/mmu_gather.c:151 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:417 [inline]
tlb_flush_mmu+0x6d3/0xa30 mm/mmu_gather.c:424
tlb_finish_mmu+0xf4/0x220 mm/mmu_gather.c:549
exit_mmap+0x4b2/0x9f0 mm/mmap.c:1313
__mmput+0x118/0x420 kernel/fork.c:1187
exit_mm+0x221/0x2d0 kernel/exit.c:615
do_exit+0x6cd/0x2360 kernel/exit.c:997
do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
__do_sys_exit_group kernel/exit.c:1163 [inline]
__se_sys_exit_group kernel/exit.c:1161 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1161
x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f69ef33e6c5
Code: Unable to access opcode bytes at 0x7f69ef33e69b.
RSP: 002b:00007ffea50cc4c8 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f69ef43ffe8 RCX: 00007f69ef33e6c5
RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f69ef43e680 R15: 00007f69ef440000
----------------
Code disassembly (best guess):
0: a4 movsb %ds:(%rsi),%es:(%rdi)
1: fe 8e 0b 67 48 0f decb 0xf48670b(%rsi)
7: b9 3a eb 4a e8 mov $0xe84aeb3a,%ecx
c: b8 21 f3 fc 48 mov $0x48fcf321,%eax
11: 8d 3d a1 fe 8e 0b lea 0xb8efea1(%rip),%edi # 0xb8efeb8
17: 67 48 0f b9 3a ud1 (%edx),%rdi
1c: eb 37 jmp 0x55
1e: e8 a5 21 f3 fc call 0xfcf321c8
23: 48 8d 3d 9e fe 8e 0b lea 0xb8efe9e(%rip),%rdi # 0xb8efec8
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: eb 24 jmp 0x55
31: e8 92 21 f3 fc call 0xfcf321c8
36: 48 8d 3d 9b fe 8e 0b lea 0xb8efe9b(%rip),%rdi # 0xb8efed8
3d: 67 addr32
3e: 48 rex.W
3f: 0f .byte 0xf