------------[ 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: syz.1.6942/31146
Modules linked in:
CPU: 0 UID: 0 PID: 31146 Comm: syz.1.6942 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: 14 d2 40 0b 67 48 0f b9 3a eb 4a e8 48 39 2a fd 48 8d 3d 11 d2 40 0b 67 48 0f b9 3a eb 37 e8 35 39 2a fd 48 8d 3d 0e d2 40 0b <67> 48 0f b9 3a eb 24 e8 22 39 2a fd 48 8d 3d 0b d2 40 0b 67 48 0f
RSP: 0018:ffffc90000007c88 EFLAGS: 00010246
RAX: ffffffff84985fbb RBX: 0000000000000003 RCX: ffff888027bdbd00
RDX: 0000000000000100 RSI: ffffffff8eae6d80 RDI: ffffffff8fd931d0
RBP: ffffc90000007d90 R08: ffff888027bdbd00 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000100 R12: 0000000000000000
R13: 00000001000178a8 R14: ffff888057435020 R15: ffff8880574351b8
FS: 00007fce4c1056c0(0000) GS:ffff888125928000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34116ff8 CR3: 0000000054c80000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000200000000300 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:preempt_schedule_irq+0x48/0xa0 kernel/sched/core.c:7194
Code: 49 be 00 00 00 00 00 fc ff df eb 09 48 f7 03 10 00 00 00 74 53 bf 01 00 00 00 e8 d3 eb 17 f6 e8 9e 8b 50 f6 fb bf 01 00 00 00 e3 a9 ff ff 9c 58 fa a9 00 02 00 00 74 05 e8 24 8d 50 f6 bf 01
RSP: 0018:ffffc90003f3f980 EFLAGS: 00000202
RAX: 0000000000008807 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8dacf9d6 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff8fced977 R09: 1ffffffff1f9db2e
R10: dffffc0000000000 R11: fffffbfff1f9db2f R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000000
irqentry_exit+0x597/0x620 kernel/entry/common.c:216
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:try_charge_memcg+0x1237/0x12a0 mm/memcontrol.c:2522
Code: 42 c6 44 20 04 f8 f7 44 24 0c 20 80 00 00 0f 85 91 fe ff ff b8 f4 ff ff ff 48 8b 4c 24 48 42 c6 44 21 0a f8 42 c6 44 21 06 f8 <48> c7 84 24 a0 00 00 00 0e 36 e0 45 4a c7 04 21 00 00 00 00 4a c7
RSP: 0018:ffffc90003f3faa0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888076888000 RCX: 1ffff920007e7f68
RDX: 0000000000000001 RSI: ffffffff8dd39273 RDI: 00000000ffffffff
RBP: ffffc90003f3fc08 R08: ffffc90003f3f6d7 R09: 0000000000000000
R10: ffffc90003f3f6c8 R11: fffff520007e7edb R12: dffffc0000000000
R13: 0000000000000040 R14: 0000000000000001 R15: ffff8880b863bd70
obj_cgroup_charge_pages+0x1e/0xa0 mm/memcontrol.c:2823
obj_cgroup_charge_account+0xcf/0x650 mm/memcontrol.c:3126
__memcg_slab_post_alloc_hook+0x3e5/0x730 mm/memcontrol.c:3212
memcg_slab_post_alloc_hook mm/slub.c:2338 [inline]
slab_post_alloc_hook mm/slub.c:4964 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_lru_noprof+0x40e/0x6c0 mm/slub.c:5282
sock_alloc_inode+0x28/0xc0 net/socket.c:322
alloc_inode+0x6a/0x1b0 fs/inode.c:346
new_inode_pseudo include/linux/fs.h:2964 [inline]
sock_alloc net/socket.c:637 [inline]
__sock_create+0x12d/0x9d0 net/socket.c:1569
sock_create net/socket.c:1663 [inline]
__sys_socket_create net/socket.c:1700 [inline]
__sys_socket+0xd6/0x1b0 net/socket.c:1747
__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+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fce4b19acb9
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:00007fce4c105028 EFLAGS: 00000246 ORIG_RAX: 0000000000000029
RAX: ffffffffffffffda RBX: 00007fce4b415fa0 RCX: 00007fce4b19acb9
RDX: 0000000000000000 RSI: 0000000400000002 RDI: 0000000000000010
RBP: 00007fce4b208bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fce4b416038 R14: 00007fce4b415fa0 R15: 00007ffdcc880198
----------------
Code disassembly (best guess):
0: 14 d2 adc $0xd2,%al
2: 40 0b 67 48 rex or 0x48(%rdi),%esp
6: 0f b9 3a ud1 (%rdx),%edi
9: eb 4a jmp 0x55
b: e8 48 39 2a fd call 0xfd2a3958
10: 48 8d 3d 11 d2 40 0b lea 0xb40d211(%rip),%rdi # 0xb40d228
17: 67 48 0f b9 3a ud1 (%edx),%rdi
1c: eb 37 jmp 0x55
1e: e8 35 39 2a fd call 0xfd2a3958
23: 48 8d 3d 0e d2 40 0b lea 0xb40d20e(%rip),%rdi # 0xb40d238
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: eb 24 jmp 0x55
31: e8 22 39 2a fd call 0xfd2a3958
36: 48 8d 3d 0b d2 40 0b lea 0xb40d20b(%rip),%rdi # 0xb40d248
3d: 67 addr32
3e: 48 rex.W
3f: 0f .byte 0xf