[moderation] [fuse?] general protection fault in fuse_dev_release

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c7275b05bc42 Add linux-next specific files for 20260417
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=112ba4ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac861e8185149d86
dashboard link: https://syzkaller.appspot.com/bug?extid=55dd926b8319c22f1a2f
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org mik...@szeredi.hu]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/02c64cb49b64/disk-c7275b05.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2703650c5cda/vmlinux-c7275b05.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4a9b28b754f3/bzImage-c7275b05.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+55dd92...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 8396 Comm: syz.4.878 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:list_empty include/linux/list.h:381 [inline]
RIP: 0010:list_splice_init include/linux/list.h:579 [inline]
RIP: 0010:fuse_dev_release+0x19c/0x670 fs/fuse/dev.c:2232
Code: 5c 24 28 48 8b 44 24 30 42 80 3c 38 00 74 08 48 89 df e8 f7 cd ec fe 48 8b 0b 48 89 4c 24 18 4e 8d 24 31 4d 89 e5 49 c1 ed 03 <43> 80 7c 3d 00 00 74 08 4c 89 e7 e8 d4 cd ec fe 4d 8b 3c 24 4d 39
RSP: 0018:ffffc90010dc7ca0 EFLAGS: 00010246
RAX: 1ffff11005543873 RBX: ffff88802aa1c398 RCX: 0000000000000000
RDX: ffffc9000fa4f000 RSI: 0000000000000031 RDI: 0000000000000032
RBP: ffffc90010dc7d80 R08: ffffffff8b38b760 R09: ffffffff8dfc8100
R10: dffffc0000000000 R11: fffffbfff1f1a83f R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS: 00007f6e760056c0(0000) GS:ffff888125eba000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6e76004ff8 CR3: 000000003e544000 CR4: 00000000003526f0
Call Trace:
<TASK>
__fput+0x461/0xa70 fs/file_table.c:510
fput_close_sync+0x11f/0x240 fs/file_table.c:615
__do_sys_close fs/open.c:1507 [inline]
__se_sys_close fs/open.c:1492 [inline]
__x64_sys_close+0x7e/0x110 fs/open.c:1492
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6e77dcc819
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:00007f6e76005028 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f6e78046090 RCX: 00007f6e77dcc819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f6e77e62c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e78046128 R14: 00007f6e78046090 R15: 00007ffe88e13f98
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:list_empty include/linux/list.h:381 [inline]
RIP: 0010:list_splice_init include/linux/list.h:579 [inline]
RIP: 0010:fuse_dev_release+0x19c/0x670 fs/fuse/dev.c:2232
Code: 5c 24 28 48 8b 44 24 30 42 80 3c 38 00 74 08 48 89 df e8 f7 cd ec fe 48 8b 0b 48 89 4c 24 18 4e 8d 24 31 4d 89 e5 49 c1 ed 03 <43> 80 7c 3d 00 00 74 08 4c 89 e7 e8 d4 cd ec fe 4d 8b 3c 24 4d 39
RSP: 0018:ffffc90010dc7ca0 EFLAGS: 00010246
RAX: 1ffff11005543873 RBX: ffff88802aa1c398 RCX: 0000000000000000
RDX: ffffc9000fa4f000 RSI: 0000000000000031 RDI: 0000000000000032
RBP: ffffc90010dc7d80 R08: ffffffff8b38b760 R09: ffffffff8dfc8100
R10: dffffc0000000000 R11: fffffbfff1f1a83f R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS: 00007f6e760056c0(0000) GS:ffff888125eba000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6e76004ff8 CR3: 000000003e544000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 5c pop %rsp
1: 24 28 and $0x28,%al
3: 48 8b 44 24 30 mov 0x30(%rsp),%rax
8: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1)
d: 74 08 je 0x17
f: 48 89 df mov %rbx,%rdi
12: e8 f7 cd ec fe call 0xfeecce0e
17: 48 8b 0b mov (%rbx),%rcx
1a: 48 89 4c 24 18 mov %rcx,0x18(%rsp)
1f: 4e 8d 24 31 lea (%rcx,%r14,1),%r12
23: 4d 89 e5 mov %r12,%r13
26: 49 c1 ed 03 shr $0x3,%r13
* 2a: 43 80 7c 3d 00 00 cmpb $0x0,0x0(%r13,%r15,1) <-- trapping instruction
30: 74 08 je 0x3a
32: 4c 89 e7 mov %r12,%rdi
35: e8 d4 cd ec fe call 0xfeecce0e
3a: 4d 8b 3c 24 mov (%r12),%r15
3e: 4d rex.WRB
3f: 39 .byte 0x39


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