[syzbot] [fs?] [io-uring?] general protection fault in __ep_remove

[syzbot <syzbot+045b454ab35fd82a35fb@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    480e035fc4c7 Merge tag 'drm-next-2024-03-13' of https://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15f55413180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1e5b814e91787669
dashboard link: https://syzkaller.appspot.com/bug?extid=045b454ab35fd82a35fb
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=101db623180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10801175180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5f73b6ef963d/disk-480e035f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/46c949396aad/vmlinux-480e035f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e3b4d0f5a5f8/bzImage-480e035f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+045b454ab35fd82a35fb@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 5075 Comm: syz-executor119 Not tainted 6.8.0-syzkaller-08073-g480e035fc4c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:__ep_remove+0x13a/0x780 fs/eventpoll.c:825
Code: 89 e7 49 c1 ef 03 41 80 3c 2f 00 74 08 4c 89 e7 e8 8b 81 d9 ff 4d 8b 34 24 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 68 81 d9 ff 49 8b 1e 48 8b 04 24 48
RSP: 0018:ffffc90003b6fa78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffff88807a310000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffffffff821ec2a4 R09: fffff5200076df40
R10: dffffc0000000000 R11: fffff5200076df40 R12: ffff88802916cbb8
R13: ffff88802916ca00 R14: 0000000000000000 R15: 1ffff1100522d977
FS:  00007f034c6ff6c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000004 CR3: 00000000775ec000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 eventpoll_release_file+0xdb/0x1c0 fs/eventpoll.c:1071
 eventpoll_release include/linux/eventpoll.h:53 [inline]
 __fput+0x6d7/0x8a0 fs/file_table.c:413
 task_work_run+0x24f/0x310 kernel/task_work.c:180
 get_signal+0x1673/0x1850 kernel/signal.c:2683
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:105 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline]
 syscall_exit_to_user_mode+0xc9/0x360 kernel/entry/common.c:212
 do_syscall_64+0x10a/0x240 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7f034c84c059
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 1f 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f034c6ff178 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f034c8f0038 RCX: 00007f034c84c059
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f034c8f0038
RBP: 00007f034c8f0030 R08: 00007f034c6ff6c0 R09: 00007f034c6ff6c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f034c8f003c
R13: 0000000000000002 R14: 00007f034c9ffc40 R15: 00007f034c9ffd28
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__ep_remove+0x13a/0x780 fs/eventpoll.c:825
Code: 89 e7 49 c1 ef 03 41 80 3c 2f 00 74 08 4c 89 e7 e8 8b 81 d9 ff 4d 8b 34 24 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 68 81 d9 ff 49 8b 1e 48 8b 04 24 48
RSP: 0018:ffffc90003b6fa78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffff88807a310000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffffffff821ec2a4 R09: fffff5200076df40
R10: dffffc0000000000 R11: fffff5200076df40 R12: ffff88802916cbb8
R13: ffff88802916ca00 R14: 0000000000000000 R15: 1ffff1100522d977
FS:  00007f034c6ff6c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000004 CR3: 00000000775ec000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	89 e7                	mov    %esp,%edi
   2:	49 c1 ef 03          	shr    $0x3,%r15
   6:	41 80 3c 2f 00       	cmpb   $0x0,(%r15,%rbp,1)
   b:	74 08                	je     0x15
   d:	4c 89 e7             	mov    %r12,%rdi
  10:	e8 8b 81 d9 ff       	call   0xffd981a0
  15:	4d 8b 34 24          	mov    (%r12),%r14
  19:	4c 89 f0             	mov    %r14,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 f7             	mov    %r14,%rdi
  33:	e8 68 81 d9 ff       	call   0xffd981a0
  38:	49 8b 1e             	mov    (%r14),%rbx
  3b:	48 8b 04 24          	mov    (%rsp),%rax
  3f:	48                   	rex.W


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