[syzbot] [io-uring?] BUG: unable to handle kernel NULL pointer dereference in percpu_ref_put_many

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    eabcdba3ad40 Merge tag 'for-6.13-rc3-tag' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10871f44580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c22efbd20f8da769
dashboard link: https://syzkaller.appspot.com/bug?extid=3dcac84cc1d50f43ed31
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=141bccf8580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=135f7730580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a9904ed2be77/disk-eabcdba3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fb8d571e1cb3/vmlinux-eabcdba3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/76349070db25/bzImage-eabcdba3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3dcac84cc1d50f43ed31@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 0 P4D 0 
Oops: Oops: 0010 [#1] PREEMPT SMP KASAN PTI
CPU: 0 UID: 0 PID: 11082 Comm: syz-executor246 Not tainted 6.13.0-rc3-syzkaller-00073-geabcdba3ad40 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc9000413f9e0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88807c722018 RCX: ffffffff8497d56c
RDX: 1ffff110287e09e1 RSI: ffffffff8497d57a RDI: ffff88807c722018
RBP: ffff888143f04f00 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000002 R12: ffff88807c722020
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880745b4a10
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000000db7e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 percpu_ref_put_many.constprop.0+0x269/0x2a0 include/linux/percpu-refcount.h:335
 percpu_ref_put include/linux/percpu-refcount.h:351 [inline]
 percpu_ref_kill_and_confirm+0x94/0x180 lib/percpu-refcount.c:396
 percpu_ref_kill include/linux/percpu-refcount.h:149 [inline]
 io_ring_ctx_wait_and_kill+0x86/0x250 io_uring/io_uring.c:2973
 io_uring_release+0x39/0x50 io_uring/io_uring.c:2995
 __fput+0x3f8/0xb60 fs/file_table.c:450
 task_work_run+0x14e/0x250 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xadd/0x2d70 kernel/exit.c:938
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
 get_signal+0x2576/0x2610 kernel/signal.c:3017
 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1575ca04e9
Code: Unable to access opcode bytes at 0x7f1575ca04bf.
RSP: 002b:00007f1575c5b218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f1575d2a308 RCX: 00007f1575ca04e9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f1575d2a308
RBP: 00007f1575d2a300 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1575d2a30c
R13: 00007f1575cf7074 R14: 006e716e5f797265 R15: 0030656c69662f2e
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc9000413f9e0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff88807c722018 RCX: ffffffff8497d56c
RDX: 1ffff110287e09e1 RSI: ffffffff8497d57a RDI: ffff88807c722018
RBP: ffff888143f04f00 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000002 R12: ffff88807c722020
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880745b4a10
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000000db7e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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