[moderation] [sctp?] WARNING: refcount bug in sctp_transport_put (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2ccec5944606 Merge tag 'erofs-for-6.18-rc6-fixes' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=179c497c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=19d831c6d0386a9c
dashboard link: https://syzkaller.appspot.com/bug?extid=00639f832844f3b63311
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
CC: [da...@davemloft.net edum...@google.com ho...@kernel.org ku...@kernel.org linux-...@vger.kernel.org linux...@vger.kernel.org lucie...@gmail.com marcelo...@gmail.com net...@vger.kernel.org pab...@redhat.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-2ccec594.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a29a7f4d52f4/vmlinux-2ccec594.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1557802e0ae5/bzImage-2ccec594.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+00639f...@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 0 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 88 82 1a fd 84 db 0f 85 66 ff ff ff e8 9b 87 1a fd c6 05 82 fe c8 0b 01 90 48 c7 c7 80 c3 ef 8b e8 b7 09 d9 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 78 87 1a fd 0f b6 1d 5d fe c8 0b 31
RSP: 0018:ffffc90000007c30 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817adc48
RDX: ffffffff8e097a00 RSI: ffffffff817adc55 RDI: 0000000000000001
RBP: ffff88806af5f820 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff88806af5f820
R13: 0000000000000101 R14: ffffffff8a96c630 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff88809780d000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000003010cffc CR3: 000000005fddc000 CR4: 0000000000352ef0
Call Trace:
<IRQ>
__refcount_sub_and_test include/linux/refcount.h:400 [inline]
__refcount_dec_and_test include/linux/refcount.h:432 [inline]
refcount_dec_and_test include/linux/refcount.h:450 [inline]
sctp_transport_put+0x12a/0x170 net/sctp/transport.c:476
call_timer_fn+0x19a/0x620 kernel/time/timer.c:1747
expire_timers kernel/time/timer.c:1798 [inline]
__run_timers+0x6ef/0x960 kernel/time/timer.c:2372
__run_timer_base kernel/time/timer.c:2384 [inline]
__run_timer_base kernel/time/timer.c:2376 [inline]
run_timer_base+0x114/0x190 kernel/time/timer.c:2393
run_timer_softirq+0x1a/0x40 kernel/time/timer.c:2403
handle_softirqs+0x219/0x8e0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x109/0x170 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1052
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 97 6f 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 83 b3 2c 00 fb f4 <e9> 3c 0a 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e007df8 EFLAGS: 00000286
RAX: 0000000000c7ee29 RBX: 0000000000000000 RCX: ffffffff8b5d72a9
RDX: 0000000000000000 RSI: ffffffff8da28539 RDI: ffffffff8bf075c0
RBP: fffffbfff1c12f40 R08: 0000000000000001 R09: ffffed1005646655
R10: ffff88802b2332ab R11: 0000000000000001 R12: 0000000000000000
R13: ffffffff8e097a00 R14: ffffffff908244d0 R15: 0000000000000000
arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
default_idle+0x13/0x20 arch/x86/kernel/process.c:767
default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:190 [inline]
do_idle+0x38d/0x500 kernel/sched/idle.c:330
cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:428
rest_init+0x16b/0x2b0 init/main.c:757
start_kernel+0x3f6/0x4e0 init/main.c:1111
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:310
x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:291
common_startup_64+0x13e/0x148
</TASK>
----------------
Code disassembly (best guess):
0: 97 xchg %eax,%edi
1: 6f outsl %ds:(%rsi),(%dx)
2: 02 c3 add %bl,%al
4: cc int3
5: cc int3
6: cc int3
7: cc int3
8: 0f 1f 00 nopl (%rax)
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 90 nop
16: 90 nop
17: 90 nop
18: 90 nop
19: 90 nop
1a: 90 nop
1b: f3 0f 1e fa endbr64
1f: eb 07 jmp 0x28
21: 0f 00 2d 83 b3 2c 00 verw 0x2cb383(%rip) # 0x2cb3ab
28: fb sti
29: f4 hlt
* 2a: e9 3c 0a 03 00 jmp 0x30a6b <-- trapping instruction
2f: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
36: 00 00 00
39: 66 90 xchg %ax,%ax
3b: 90 nop
3c: 90 nop
3d: 90 nop
3e: 90 nop
3f: 90 nop


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