------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#1: syz.2.8809/9588
Modules linked in:
CPU: 1 UID: 0 PID: 9588 Comm: syz.2.8809 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: 54 64 75 0b 67 48 0f b9 3a eb 4a e8 68 40 1e fd 48 8d 3d 51 64 75 0b 67 48 0f b9 3a eb 37 e8 55 40 1e fd 48 8d 3d 4e 64 75 0b <67> 48 0f b9 3a eb 24 e8 42 40 1e fd 48 8d 3d 4b 64 75 0b 67 48 0f
RSP: 0018:ffffc90000a08c88 EFLAGS: 00010246
RAX: ffffffff84a672cb RBX: 0000000000000003 RCX: ffff888046a81e40
RDX: 0000000000000100 RSI: ffffffff8eefc880 RDI: ffffffff901bd720
RBP: ffffc90000a08d90 R08: ffff888046a81e40 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000100 R12: 0000000000000001
R13: 0000000100026130 R14: ffff88806de3c020 R15: ffff88806de3c1b8
FS: 00007f957a6bf6c0(0000) GS:ffff888125596000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f957a69dff8 CR3: 000000007bdc4000 CR4: 00000000003526f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
call_timer_fn+0x192/0x5a0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2373 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2385
run_timer_base kernel/time/timer.c:2394 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
handle_softirqs+0x22a/0x7c0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__schedule+0x13d/0x52b0 kernel/sched/core.c:-1
Code: 08 48 89 df e8 54 8d 8c f6 4c 8b 23 49 8d 9c 24 98 4b 1a 93 49 89 df 49 c1 ef 03 43 80 3c 37 00 74 08 48 89 df e8 33 8d 8c f6 <48> 89 5c 24 38 48 8b 03 48 89 44 24 10 48 8d 58 20 48 89 d8 48 c1
RSP: 0018:ffffc9000c537460 EFLAGS: 00000246
RAX: 1ffffffff1c344f3 RBX: ffff8880b873ab98 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8c278860 RDI: ffffffff8c278820
RBP: ffffc9000c537660 R08: ffffffff90111eb7 R09: 1ffffffff20223d6
R10: dffffc0000000000 R11: fffffbfff20223d7 R12: ffff888125596000
R13: 0000000000000001 R14: dffffc0000000000 R15: 1ffff110170e7573
preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7234
irqentry_exit+0x599/0x620 kernel/entry/common.c:239
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:unwind_next_frame+0x181c/0x23c0 arch/x86/kernel/unwind_orc.c:-1
Code: a4 0c 01 0f 85 19 02 00 00 80 3d 0e e7 a8 11 00 0f 85 0c 02 00 00 c6 05 01 e7 a8 11 01 4c 89 f7 e8 b9 0b 00 00 e9 f8 01 00 00 <48> 8b 54 24 08 48 8d 5a 02 48 83 c2 03 48 89 d8 48 c1 e8 03 0f b6
RSP: 0018:ffffc9000c537798 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc9000c537900 RCX: 0000000000000000
RDX: ffffffff90a455ca RSI: 0000000000000001 RDI: ffffc9000c537928
RBP: dffffc0000000000 R08: ffffc9000c537927 R09: 0000000000000000
R10: ffffc9000c537918 R11: fffff520018a6f25 R12: ffffc9000c537918
R13: 1ffff920018a6f1b R14: ffffc9000c5378c8 R15: 1ffffffff2148ab9
__unwind_start+0x5b8/0x760 arch/x86/kernel/unwind_orc.c:773
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xe3/0x150 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4459 [inline]
slab_alloc_node mm/slub.c:4788 [inline]
kmem_cache_alloc_lru_noprof+0x2b8/0x640 mm/slub.c:4807
__d_alloc+0x37/0x6f0 fs/dcache.c:1740
d_alloc_pseudo+0x21/0xc0 fs/dcache.c:1871
alloc_path_pseudo fs/file_table.c:364 [inline]
alloc_file_pseudo+0xdd/0x240 fs/file_table.c:380
sock_alloc_file+0xb8/0x2e0 net/socket.c:483
sock_map_fd net/socket.c:513 [inline]
__sys_socket+0x13c/0x1b0 net/socket.c:1756
__do_sys_socket net/socket.c:1761 [inline]
__se_sys_socket net/socket.c:1759 [inline]
__x64_sys_socket+0x7a/0x90 net/socket.c:1759
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f957979c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f957a6bf028 EFLAGS: 00000246 ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 00007f9579a15fa0 RCX: 00007f957979c629
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 000000000000000a
RBP: 00007f9579832b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9579a16038 R14: 00007f9579a15fa0 R15: 00007ffe31b398a8
----------------
Code disassembly (best guess):
0: 54 push %rsp
1: 64 75 0b fs jne 0xf
4: 67 48 0f b9 3a ud1 (%edx),%rdi
9: eb 4a jmp 0x55
b: e8 68 40 1e fd call 0xfd1e4078
10: 48 8d 3d 51 64 75 0b lea 0xb756451(%rip),%rdi # 0xb756468
17: 67 48 0f b9 3a ud1 (%edx),%rdi
1c: eb 37 jmp 0x55
1e: e8 55 40 1e fd call 0xfd1e4078
23: 48 8d 3d 4e 64 75 0b lea 0xb75644e(%rip),%rdi # 0xb756478
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: eb 24 jmp 0x55
31: e8 42 40 1e fd call 0xfd1e4078
36: 48 8d 3d 4b 64 75 0b lea 0xb75644b(%rip),%rdi # 0xb756488
3d: 67 addr32
3e: 48 rex.W
3f: 0f .byte 0xf