[syzbot] [mm?] BUG: unable to handle kernel paging request in vma_merge_existing_range

[syzbot <syzbot+20ed41006cf9d842c2b5@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    eb88e6bfbc0a Merge tag 'fsnotify_for_v6.14-rc7' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11e6c83f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=77423669c2b8fa9
dashboard link: https://syzkaller.appspot.com/bug?extid=20ed41006cf9d842c2b5
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-eb88e6bf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ded0ce69669f/vmlinux-eb88e6bf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6e6fa3c719e7/bzImage-eb88e6bf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+20ed41006cf9d842c2b5@syzkaller.appspotmail.com

RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
BUG: unable to handle page fault for address: fffffffffffffff4
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD df84067 P4D df84067 PUD df86067 PMD 0 
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 1 UID: 0 PID: 17805 Comm: syz.8.3237 Not tainted 6.14.0-rc6-syzkaller-00212-geb88e6bfbc0a #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:vma_merge_existing_range+0x266/0x2070 mm/vma.c:734
Code: e8 5f 25 ad ff 48 8b 14 24 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 1c 19 00 00 48 8b 04 24 48 8b 74 24 08 <4c> 8b 38 4c 89 ff e8 9f 1f ad ff 48 8b 44 24 08 49 39 c7 0f 83 db
RSP: 0000:ffffc9000319f988 EFLAGS: 00010246
RAX: fffffffffffffff4 RBX: ffffc9000319fae8 RCX: ffffffff820cd3e5
RDX: 1ffffffffffffffe RSI: 0000000080c2a000 RDI: 0000000000000005
RBP: 0000000080ce2000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001
R13: ffffc9000319fb08 R14: ffff888025eddc98 R15: ffff88804eec0a00
FS:  0000000000000000(0000) GS:ffff88802b500000(0063) knlGS:00000000f5106b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: fffffffffffffff4 CR3: 00000000614d6000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vma_modify.constprop.0+0x87/0x410 mm/vma.c:1517
 vma_modify_flags_uffd+0x241/0x2e0 mm/vma.c:1598
 userfaultfd_clear_vma+0x91/0x130 mm/userfaultfd.c:1906
 userfaultfd_release_all+0x2ae/0x4c0 mm/userfaultfd.c:2024
 userfaultfd_release+0xf4/0x1c0 fs/userfaultfd.c:865
 __fput+0x3ff/0xb70 fs/file_table.c:464
 task_work_run+0x14e/0x250 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [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+0x27b/0x2a0 kernel/entry/common.c:218
 __do_fast_syscall_32+0x80/0x120 arch/x86/entry/common.c:390
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:412
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7fe6579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f510655c EFLAGS: 00000296 ORIG_RAX: 0000000000000135
RAX: 0000000000000001 RBX: 0000000080000180 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
CR2: fffffffffffffff4
---[ end trace 0000000000000000 ]---
RIP: 0010:vma_merge_existing_range+0x266/0x2070 mm/vma.c:734
Code: e8 5f 25 ad ff 48 8b 14 24 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 1c 19 00 00 48 8b 04 24 48 8b 74 24 08 <4c> 8b 38 4c 89 ff e8 9f 1f ad ff 48 8b 44 24 08 49 39 c7 0f 83 db
RSP: 0000:ffffc9000319f988 EFLAGS: 00010246
RAX: fffffffffffffff4 RBX: ffffc9000319fae8 RCX: ffffffff820cd3e5
RDX: 1ffffffffffffffe RSI: 0000000080c2a000 RDI: 0000000000000005
RBP: 0000000080ce2000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001
R13: ffffc9000319fb08 R14: ffff888025eddc98 R15: ffff88804eec0a00
FS:  0000000000000000(0000) GS:ffff88802b500000(0063) knlGS:00000000f5106b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: fffffffffffffff4 CR3: 00000000614d6000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	e8 5f 25 ad ff       	call   0xffad2564
   5:	48 8b 14 24          	mov    (%rsp),%rdx
   9:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  10:	fc ff df
  13:	48 c1 ea 03          	shr    $0x3,%rdx
  17:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
  1b:	0f 85 1c 19 00 00    	jne    0x193d
  21:	48 8b 04 24          	mov    (%rsp),%rax
  25:	48 8b 74 24 08       	mov    0x8(%rsp),%rsi
* 2a:	4c 8b 38             	mov    (%rax),%r15 <-- trapping instruction
  2d:	4c 89 ff             	mov    %r15,%rdi
  30:	e8 9f 1f ad ff       	call   0xffad1fd4
  35:	48 8b 44 24 08       	mov    0x8(%rsp),%rax
  3a:	49 39 c7             	cmp    %rax,%r15
  3d:	0f                   	.byte 0xf
  3e:	83                   	.byte 0x83
  3f:	db                   	.byte 0xdb


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