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

[syzbot <syzbot+2403e3909382fbdeaf6c@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    43db1e03c086 Merge tag 'for-6.10/dm-fixes-2' of git://git...
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16f39ee1980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=42a432cfd0e579e0
dashboard link: https://syzkaller.appspot.com/bug?extid=2403e3909382fbdeaf6c
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=141c864e980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12b1da7e980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/709e8f085073/disk-43db1e03.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1ab1fd5e8c1c/vmlinux-43db1e03.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dc7484cb3765/bzImage-43db1e03.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/40d14eae864b/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2403e3909382fbdeaf6c@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 1 PID: 5077 Comm: syz-executor294 Not tainted 6.10.0-rc7-syzkaller-00141-g43db1e03c086 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
RIP: 0010:list_add_tail include/linux/list.h:183 [inline]
RIP: 0010:list_lru_add+0x1b1/0x390 mm/list_lru.c:97
Code: 89 ef e8 e2 06 1c 00 48 8b 45 00 48 8b 4c 24 30 48 8d 6c 08 40 4c 8d 6d 08 4d 89 ec 49 c1 ec 03 48 b8 00 00 00 00 00 fc ff df <41> 80 3c 04 00 74 08 4c 89 ef e8 b0 06 1c 00 4c 8b 7d 08 4c 89 f7
RSP: 0018:ffffc90003bbfa78 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 1ffff1100fada037 RCX: 0000000000000000
RDX: 0000000000000003 RSI: ffffffff8bcaccc0 RDI: ffffffff8c1f54c0
RBP: 0000000000000000 R08: ffffffff8fac686f R09: 1ffffffff1f58d0d
R10: dffffc0000000000 R11: fffffbfff1f58d0e R12: 0000000000000001
R13: 0000000000000008 R14: ffff88807d6d01b8 R15: 0000000000000000
FS:  000055557a070380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045bdd0 CR3: 0000000023864000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __inode_add_lru fs/inode.c:467 [inline]
 iput_final fs/inode.c:1718 [inline]
 iput+0x87a/0x930 fs/inode.c:1767
 __dentry_kill+0x20d/0x630 fs/dcache.c:607
 dput+0x19f/0x2b0 fs/dcache.c:849
 shrink_dcache_for_umount+0x7d/0x130 fs/dcache.c:1559
 generic_shutdown_super+0x6a/0x2d0 fs/super.c:620
 bch2_kill_sb+0x41/0x50 fs/bcachefs/fs.c:2052
 deactivate_locked_super+0xc4/0x130 fs/super.c:473
 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1267
 task_work_run+0x24f/0x310 kernel/task_work.c:180
 ptrace_notify+0x2d2/0x380 kernel/signal.c:2402
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0xc6/0x190 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x273/0x360 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f232c4c5e77
Code: 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fffde2e9f38 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f232c4c5e77
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffde2e9ff0
RBP: 00007fffde2e9ff0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000202 R12: 00007fffde2eb060
R13: 000055557a0716c0 R14: 00007fffde2eb05c R15: 431bde82d7b634db
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:list_add_tail include/linux/list.h:183 [inline]
RIP: 0010:list_lru_add+0x1b1/0x390 mm/list_lru.c:97
Code: 89 ef e8 e2 06 1c 00 48 8b 45 00 48 8b 4c 24 30 48 8d 6c 08 40 4c 8d 6d 08 4d 89 ec 49 c1 ec 03 48 b8 00 00 00 00 00 fc ff df <41> 80 3c 04 00 74 08 4c 89 ef e8 b0 06 1c 00 4c 8b 7d 08 4c 89 f7
RSP: 0018:ffffc90003bbfa78 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 1ffff1100fada037 RCX: 0000000000000000
RDX: 0000000000000003 RSI: ffffffff8bcaccc0 RDI: ffffffff8c1f54c0
RBP: 0000000000000000 R08: ffffffff8fac686f R09: 1ffffffff1f58d0d
R10: dffffc0000000000 R11: fffffbfff1f58d0e R12: 0000000000000001
R13: 0000000000000008 R14: ffff88807d6d01b8 R15: 0000000000000000
FS:  000055557a070380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045bdd0 CR3: 0000000023864000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	89 ef                	mov    %ebp,%edi
   2:	e8 e2 06 1c 00       	call   0x1c06e9
   7:	48 8b 45 00          	mov    0x0(%rbp),%rax
   b:	48 8b 4c 24 30       	mov    0x30(%rsp),%rcx
  10:	48 8d 6c 08 40       	lea    0x40(%rax,%rcx,1),%rbp
  15:	4c 8d 6d 08          	lea    0x8(%rbp),%r13
  19:	4d 89 ec             	mov    %r13,%r12
  1c:	49 c1 ec 03          	shr    $0x3,%r12
  20:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  27:	fc ff df
* 2a:	41 80 3c 04 00       	cmpb   $0x0,(%r12,%rax,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 ef             	mov    %r13,%rdi
  34:	e8 b0 06 1c 00       	call   0x1c06e9
  39:	4c 8b 7d 08          	mov    0x8(%rbp),%r15
  3d:	4c 89 f7             	mov    %r14,%rdi


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