divide error in squashfs_readpage

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 87335852 Linux 4.14.209
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1086a453500000
kernel config: https://syzkaller.appspot.com/x/.config?x=77df3f7a7cfbd2e6
dashboard link: https://syzkaller.appspot.com/bug?extid=b260f9c55a014c009739
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13c30163500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17917c0d500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b260f9...@syzkaller.appspotmail.com

divide error: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7982 Comm: syz-executor083 Not tainted 4.14.209-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880b5300000 task.stack: ffff888096358000
RIP: 0010:fill_meta_index fs/squashfs/file.c:256 [inline]
RIP: 0010:read_blocklist fs/squashfs/file.c:345 [inline]
RIP: 0010:squashfs_readpage+0x7a0/0x1d5d fs/squashfs/file.c:482
RSP: 0018:ffff88809635f798 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffea0002400680 RDI: ffff88808df9a4f8
RBP: 0000000000000099 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000000000de
R13: ffff88808df9a548 R14: ffffea0002400690 R15: ffffea0002400688
FS: 0000000000ed8880(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055fe05c98020 CR3: 00000000b5384000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
read_pages mm/readahead.c:131 [inline]
__do_page_cache_readahead+0x69b/0x940 mm/readahead.c:199
ra_submit mm/internal.h:66 [inline]
ondemand_readahead.isra.0+0x514/0xb60 mm/readahead.c:486
page_cache_sync_readahead mm/readahead.c:518 [inline]
page_cache_sync_readahead+0xa6/0xf0 mm/readahead.c:503
generic_file_buffered_read mm/filemap.c:2003 [inline]
generic_file_read_iter+0xfbc/0x21c0 mm/filemap.c:2273
call_read_iter include/linux/fs.h:1772 [inline]
new_sync_read fs/read_write.c:401 [inline]
__vfs_read+0x449/0x620 fs/read_write.c:413
vfs_read+0x139/0x340 fs/read_write.c:447
kernel_read+0xa6/0x110 fs/read_write.c:426
prepare_binprm+0x5b8/0x7e0 fs/exec.c:1581
do_execveat_common+0xd72/0x1f30 fs/exec.c:1798
do_execveat fs/exec.c:1871 [inline]
SYSC_execveat fs/exec.c:1952 [inline]
SyS_execveat+0x51/0x70 fs/exec.c:1944
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4443c9
RSP: 002b:00007fffaa0dde68 EFLAGS: 00000246 ORIG_RAX: 0000000000000142
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 00000000004443c9
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000005
RBP: 00000000006cf018 R08: 0000000000000000 R09: 00000000004002e0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401fb0
R13: 0000000000402040 R14: 0000000000000000 R15: 0000000000000000
Code: 89 a4 24 d0 00 00 00 80 3c 02 00 0f 85 77 15 00 00 48 63 8c 24 94 00 00 00 31 d2 48 63 44 24 50 48 8b 3c 24 48 89 cb 48 c1 e1 0b <48> f7 f1 c1 e3 0b 85 c0 48 89 44 24 60 4c 8b 6f c8 89 44 24 38
RIP: fill_meta_index fs/squashfs/file.c:256 [inline] RSP: ffff88809635f798
RIP: read_blocklist fs/squashfs/file.c:345 [inline] RSP: ffff88809635f798
RIP: squashfs_readpage+0x7a0/0x1d5d fs/squashfs/file.c:482 RSP: ffff88809635f798
---[ end trace 97236d6cdc65c556 ]---


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