[syzbot] UBSAN: array-index-out-of-bounds in dbAllocBits

From: syzbot
Date: Tue Oct 04 2022 - 05:01:03 EST


syzbot found the following issue on:

HEAD commit: 4fe89d07dcc2 Linux 6.0
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=123b2034880000
kernel config: https://syzkaller.appspot.com/x/.config?x=a1c7bd9b9b7d4c47
dashboard link: https://syzkaller.appspot.com/bug?extid=ae2f5a27a07ae44b0f17
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=122f6fc0880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12330ccc880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/90e404873893/disk-4fe89d07.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/010b08fa7faf/vmlinux-4fe89d07.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ae2f5a27a07ae44b0f17@xxxxxxxxxxxxxxxxxxxxxxxxx

loop0: detected capacity change from 0 to 32768
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:2222:23
index 128 is out of range for type 's64 [128]'
CPU: 0 PID: 3605 Comm: syz-executor514 Not tainted 6.0.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
ubsan_epilogue+0xb/0x50 lib/ubsan.c:151
__ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:283
dbAllocBits+0x50f/0x5f0 fs/jfs/jfs_dmap.c:2222
dbAllocDmap+0x61/0x110 fs/jfs/jfs_dmap.c:1999
dbAllocNext+0x34a/0x410 fs/jfs/jfs_dmap.c:1152
dbAlloc+0x323/0xa70 fs/jfs/jfs_dmap.c:786
extBalloc fs/jfs/jfs_extent.c:321 [inline]
extAlloc+0x4e7/0xeb0 fs/jfs/jfs_extent.c:122
jfs_get_block+0x661/0xa90 fs/jfs/inode.c:248
__block_write_begin_int+0x3ca/0x1520 fs/buffer.c:2006
__block_write_begin fs/buffer.c:2056 [inline]
block_write_begin+0xb5/0x4d0 fs/buffer.c:2117
jfs_write_begin+0x2d/0xd0 fs/jfs/inode.c:304
generic_perform_write+0x246/0x560 mm/filemap.c:3738
__generic_file_write_iter+0x2aa/0x4d0 mm/filemap.c:3866
generic_file_write_iter+0xdf/0x350 mm/filemap.c:3898
call_write_iter include/linux/fs.h:2187 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x9e9/0xdd0 fs/read_write.c:584
ksys_write+0x127/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
RIP: 0033:0x7fc695c29e59
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd7dbbb058 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc695c29e59
RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000003
RBP: 00007fc695be9620 R08: 0000000000000000 R09: 00007fc695be9620
R10: 00005555574562c0 R11: 0000000000000246 R12: 0000000200000004
R13: 0000000000000000 R14: 00080000000000f8 R15: 0000000000000000

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