divide error in squashfs_readpage

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 13d2ce42 Linux 4.19.163
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17bbad37500000
kernel config: https://syzkaller.appspot.com/x/.config?x=fac7c3360835a4e0
dashboard link: https://syzkaller.appspot.com/bug?extid=68c8ae328649eebf2b5a
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=127d845b500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13e678a7500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+68c8ae...@syzkaller.appspotmail.com

divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 8127 Comm: syz-executor882 Not tainted 4.19.163-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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+0x93d/0x20e5 fs/squashfs/file.c:482
Code: 34 24 31 d2 48 63 8c 24 9c 00 00 00 49 8b 46 c8 48 89 cf 48 c1 e1 0b c1 e7 0b 89 7c 24 3c 31 ff 48 89 44 24 58 48 63 44 24 60 <48> f7 f1 49 89 c7 89 c6 48 89 44 24 50 89 44 24 1c 89 44 24 38 e8
RSP: 0018:ffff88809531f5d0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000099 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81f7485f RDI: 0000000000000000
RBP: ffff8880b016c0c0 R08: 0000000000000001 R09: ffffffffffffffff
R10: 0000000000000007 R11: 0000000000000000 R12: 00000000000000de
R13: 0000000fffffff11 R14: ffff88808ac1e4f8 R15: 0000000000000000
FS: 0000000000fb2880(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fef83b00f60 CR3: 00000000a89d5000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
read_pages.isra.0+0x329/0x5d0 mm/readahead.c:133
__do_page_cache_readahead+0x5c6/0x6c0 mm/readahead.c:211
ra_submit mm/internal.h:66 [inline]
ondemand_readahead.isra.0+0x575/0xd40 mm/readahead.c:493
page_cache_sync_readahead mm/readahead.c:528 [inline]
page_cache_sync_readahead+0x275/0x520 mm/readahead.c:510
generic_file_buffered_read mm/filemap.c:2115 [inline]
generic_file_read_iter+0x1497/0x2b60 mm/filemap.c:2385
call_read_iter include/linux/fs.h:1815 [inline]
new_sync_read fs/read_write.c:406 [inline]
__vfs_read+0x518/0x750 fs/read_write.c:418
vfs_read+0x194/0x3c0 fs/read_write.c:452
kernel_read+0xa6/0x110 fs/read_write.c:431
prepare_binprm+0x64f/0x890 fs/exec.c:1596
__do_execve_file+0xfb8/0x2360 fs/exec.c:1815
do_execveat_common fs/exec.c:1879 [inline]
do_execveat+0x3d/0x50 fs/exec.c:1907
__do_sys_execveat fs/exec.c:1988 [inline]
__se_sys_execveat fs/exec.c:1980 [inline]
__x64_sys_execveat+0xe1/0x120 fs/exec.c:1980
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4443c9
Code: 8d d7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 5b d7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd6703ed98 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
Modules linked in:
---[ end trace c1544e0511967122 ]---
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+0x93d/0x20e5 fs/squashfs/file.c:482
Code: 34 24 31 d2 48 63 8c 24 9c 00 00 00 49 8b 46 c8 48 89 cf 48 c1 e1 0b c1 e7 0b 89 7c 24 3c 31 ff 48 89 44 24 58 48 63 44 24 60 <48> f7 f1 49 89 c7 89 c6 48 89 44 24 50 89 44 24 1c 89 44 24 38 e8
RSP: 0018:ffff88809531f5d0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000099 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81f7485f RDI: 0000000000000000
RBP: ffff8880b016c0c0 R08: 0000000000000001 R09: ffffffffffffffff
R10: 0000000000000007 R11: 0000000000000000 R12: 00000000000000de
R13: 0000000fffffff11 R14: ffff88808ac1e4f8 R15: 0000000000000000
FS: 0000000000fb2880(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fef83b00f60 CR3: 00000000a89d5000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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