[Android 5.10] BUG: unable to handle kernel NULL pointer dereference in snapshot_merge_next_chunks

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f61a392235e0 Merge 5.10.272 into android13-5.10-lts
git tree: android13-5.10-lts
console+strace: https://syzkaller.appspot.com/x/log.txt?x=103f94d9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=40fa24cc6888ca30
dashboard link: https://syzkaller.appspot.com/bug?extid=c9e10ebadd9f696a08f4
compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=112f67a5580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10a9583d580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1067764b73c1/disk-f61a3922.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/eda1b07ee362/vmlinux-f61a3922.xz
kernel image: https://storage.googleapis.com/syzbot-assets/109d1701bea2/bzImage-f61a3922.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c9e10e...@syzkaller.appspotmail.com

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 0 P4D 0
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 297 Comm: syz-executor165 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90000b878d8 EFLAGS: 00010246

RAX: 1ffffffff0d3836f RBX: 1ffff11023f02a31 RCX: dffffc0000000000
RDX: ffffc90000b87980 RSI: ffffc90000b87960 RDI: ffff8881067ce400
RBP: ffffc90000b87ad0 R08: ffff88811f8151bf R09: 1ffff11023f02a37
R10: dffffc0000000000 R11: ffffed1023f02a38 R12: ffff88811f8151b8
R13: ffff88811f815188 R14: ffffffff869c1b78 R15: ffff8881067ce400
FS: 00005555810233c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000104dca000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
snapshot_merge_next_chunks+0x249/0xbb0 drivers/md/dm-snap.c:1064
start_merge drivers/md/dm-snap.c:1186 [inline]
snapshot_merge_resume+0x24f/0x2a0 drivers/md/dm-snap.c:2334
dm_table_resume_targets+0x222/0x360 drivers/md/dm-table.c:2282
__dm_resume+0x25/0x180 drivers/md/dm.c:2611
dm_resume+0x1c3/0x240 drivers/md/dm.c:2656
do_resume drivers/md/dm-ioctl.c:1103 [inline]
dev_suspend+0x2ae/0x5d0 drivers/md/dm-ioctl.c:1131
ctl_ioctl drivers/md/dm-ioctl.c:1925 [inline]
dm_ctl_ioctl+0x8ee/0xca0 drivers/md/dm-ioctl.c:1947
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:739
__x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f37c68a8039
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe0a9b32e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffe0a9b3418 RCX: 00007f37c68a8039
RDX: 0000200000000740 RSI: 00000000c138fd06 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffe0a9b3418 R09: 00007ffe0a9b3418
R10: 0000000000000013 R11: 0000000000000246 R12: 00007ffe0a9b3408
R13: 0000000000000002 R14: 00007f37c6938ca0 R15: 0000000000000002
Modules linked in:
CR2: 0000000000000000
---[ end trace a3375c11c9cf400b ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90000b878d8 EFLAGS: 00010246
RAX: 1ffffffff0d3836f RBX: 1ffff11023f02a31 RCX: dffffc0000000000
RDX: ffffc90000b87980 RSI: ffffc90000b87960 RDI: ffff8881067ce400
RBP: ffffc90000b87ad0 R08: ffff88811f8151bf R09: 1ffff11023f02a37
R10: dffffc0000000000 R11: ffffed1023f02a38 R12: ffff88811f8151b8
R13: ffff88811f815188 R14: ffffffff869c1b78 R15: ffff8881067ce400
FS: 00005555810233c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000104dca000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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