syzbot
BUG: unable to handle kernel paging request in snapshot_merge_next_chunks
Status:
premoderation: reported on 2026/11/08 02:13
Reported-by: syzbot+2a119c9af8602ae04f54@syzkaller.appspotmail.com
First crash: 21h18m, last: 21h18m
Sample crash report:
device-mapper: table: 252:1: crypt: Device lookup failed (-ENODEV)
device-mapper: ioctl: error adding target to table
BUG: unable to handle page fault for address: fffffffffffffffc
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 7012067 P4D 7012067 PUD 7014067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 7408 Comm: syz.2.1613 Tainted: G W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
RIP: 0010:snapshot_merge_next_chunks+0x26c/0xca0 drivers/md/dm-snap.c:1056
Code: 83 c3 38 48 89 d8 48 c1 e8 03 80 3c 08 00 74 08 48 89 df e8 f6 30 2a fe 4c 89 ff 4c 89 e6 4c 89 ea 4c 8b 1b 41 ba 5d d2 f4 ae <45> 03 53 fc 74 02 0f 0b 41 ff d3 89 c3 bf 01 00 00 00 89 c6 e8 fb
RSP: 0018:ffffc90002c7f8a0 EFLAGS: 00010246
RAX: 1ffffffff0ec86d7 RBX: ffffffff876436b8 RCX: dffffc0000000000
RDX: ffffc90002c7f940 RSI: ffffc90002c7f920 RDI: ffff888136b37100
RBP: ffffc90002c7fa90 R08: ffff88810ecce9bf R09: 1ffff11021d99d37
R10: 00000000aef4d25d R11: 0000000000000000 R12: ffffc90002c7f920
R13: ffffc90002c7f940 R14: ffff88810ecce9b8 R15: ffff888136b37100
FS: 00007f39c39c66c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 000000011aa81000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 000000000000000c DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
start_merge drivers/md/dm-snap.c:1166 [inline]
snapshot_merge_resume+0x252/0x2a0 drivers/md/dm-snap.c:2309
dm_table_resume_targets+0x243/0x380 drivers/md/dm-table.c:2189
__dm_resume+0x25/0x1b0 drivers/md/dm.c:2822
dm_resume+0x166/0x1e0 drivers/md/dm.c:2867
do_resume drivers/md/dm-ioctl.c:1199 [inline]
dev_suspend+0x3fb/0x700 drivers/md/dm-ioctl.c:1231
ctl_ioctl drivers/md/dm-ioctl.c:2040 [inline]
dm_ctl_ioctl+0x95f/0xd00 drivers/md/dm-ioctl.c:2062
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0x12f/0x1b0 fs/ioctl.c:856
__x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:856
x64_sys_call+0x58b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f39c2b9fb19
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:00007f39c39c6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f39c2e25fa0 RCX: 00007f39c2b9fb19
RDX: 0000200000000400 RSI: 00000000c138fd06 RDI: 0000000000000005
RBP: 00007f39c2c37b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f39c2e26038 R14: 00007f39c2e25fa0 R15: 00007ffc3087f8e8
</TASK>
Modules linked in:
CR2: fffffffffffffffc
---[ end trace 0000000000000000 ]---
RIP: 0010:snapshot_merge_next_chunks+0x26c/0xca0 drivers/md/dm-snap.c:1056
Code: 83 c3 38 48 89 d8 48 c1 e8 03 80 3c 08 00 74 08 48 89 df e8 f6 30 2a fe 4c 89 ff 4c 89 e6 4c 89 ea 4c 8b 1b 41 ba 5d d2 f4 ae <45> 03 53 fc 74 02 0f 0b 41 ff d3 89 c3 bf 01 00 00 00 89 c6 e8 fb
RSP: 0018:ffffc90002c7f8a0 EFLAGS: 00010246
RAX: 1ffffffff0ec86d7 RBX: ffffffff876436b8 RCX: dffffc0000000000
RDX: ffffc90002c7f940 RSI: ffffc90002c7f920 RDI: ffff888136b37100
RBP: ffffc90002c7fa90 R08: ffff88810ecce9bf R09: 1ffff11021d99d37
R10: 00000000aef4d25d R11: 0000000000000000 R12: ffffc90002c7f920
R13: ffffc90002c7f940 R14: ffff88810ecce9b8 R15: ffff888136b37100
FS: 00007f39c39c66c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 000000011aa81000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 000000000000000c DR6: 00000000ffff0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 83 c3 38 add $0x38,%ebx
3: 48 89 d8 mov %rbx,%rax
6: 48 c1 e8 03 shr $0x3,%rax
a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1)
e: 74 08 je 0x18
10: 48 89 df mov %rbx,%rdi
13: e8 f6 30 2a fe call 0xfe2a310e
18: 4c 89 ff mov %r15,%rdi
1b: 4c 89 e6 mov %r12,%rsi
1e: 4c 89 ea mov %r13,%rdx
21: 4c 8b 1b mov (%rbx),%r11
24: 41 ba 5d d2 f4 ae mov $0xaef4d25d,%r10d
* 2a: 45 03 53 fc add -0x4(%r11),%r10d <-- trapping instruction
2e: 74 02 je 0x32
30: 0f 0b ud2
32: 41 ff d3 call *%r11
35: 89 c3 mov %eax,%ebx
37: bf 01 00 00 00 mov $0x1,%edi
3c: 89 c6 mov %eax,%esi
3e: e8 .byte 0xe8
3f: fb sti
* Struck through repros no longer work on HEAD.