kernel BUG in dbFindLeaf

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9d5c0b3a8e1a Linux 4.14.295
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10bdac82880000
kernel config: https://syzkaller.appspot.com/x/.config?x=746c079015a92425
dashboard link: https://syzkaller.appspot.com/bug?extid=65d1c2f1467906ad3ad7
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=160f76f4880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b255e0880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ed6fcf5895a2/disk-9d5c0b3a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/341aa3534116/vmlinux-9d5c0b3a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+65d1c2...@syzkaller.appspotmail.com

BUG at fs/jfs/jfs_dmap.c:3010 assert(n < 4)
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kernel BUG at fs/jfs/jfs_dmap.c:3010!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7979 Comm: syz-executor163 Not tainted 4.14.295-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
task: ffff8880b2d90580 task.stack: ffff8880977d8000
RIP: 0010:dbFindLeaf+0x110/0x200 fs/jfs/jfs_dmap.c:3010
RSP: 0018:ffff8880977df598 EFLAGS: 00010286
RAX: 000000000000002b RBX: 000000000000001d RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff878bc9e0 RDI: ffffed1012efbea9
RBP: ffff8880b610c010 R08: 000000000000002b R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 000000000000001d
R13: 0000000000000000 R14: dffffc0000000000 R15: 00000000001cb702
FS: 0000555555e2d300(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ec3d3e4008 CR3: 00000000ae73a000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
dbAllocDmapLev+0x87/0x280 fs/jfs/jfs_dmap.c:2018
dbAlloc+0x6e9/0x980 fs/jfs/jfs_dmap.c:838
extBalloc fs/jfs/jfs_extent.c:531 [inline]
extAlloc+0x478/0xc20 fs/jfs/jfs_extent.c:138
jfs_get_block+0x1be/0x950 fs/jfs/inode.c:259
nobh_write_begin+0x368/0xc10 fs/buffer.c:2676
jfs_write_begin+0x3e/0x190 fs/jfs/inode.c:324
generic_perform_write+0x1c9/0x420 mm/filemap.c:3055
__generic_file_write_iter+0x227/0x590 mm/filemap.c:3180
generic_file_write_iter+0x36f/0x650 mm/filemap.c:3208
call_write_iter include/linux/fs.h:1780 [inline]
do_iter_readv_writev+0x4cf/0x5f0 fs/read_write.c:675
do_iter_write+0x152/0x550 fs/read_write.c:954
vfs_writev+0x125/0x290 fs/read_write.c:999
do_writev+0xfc/0x2c0 fs/read_write.c:1034
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f847f9d2e59
RSP: 002b:00007ffe02cce0a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f847f9d2e59
RDX: 0000000000000001 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00007f847f9926c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000f8008000
R13: 0000000000000000 R14: 00080000000000f4 R15: 0000000000000000
Code: c3 01 44 39 e3 75 be e8 ff 30 1a ff 48 c7 c1 40 a2 b6 87 ba c2 0b 00 00 48 c7 c6 c0 a1 b6 87 48 c7 c7 00 a2 b6 87 e8 65 ba c7 04 <0f> 0b e8 d9 30 1a ff 8d 04 9d 01 00 00 00 41 83 ef 01 75 80 e8
RIP: dbFindLeaf+0x110/0x200 fs/jfs/jfs_dmap.c:3010 RSP: ffff8880977df598
---[ end trace d1b3db956d7eb755 ]---


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