divide error in read_super_block

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    d45331b0 Linux 5.3-rc4
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17f9879a600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3d7eaed8496da4da
dashboard link: https://syzkaller.appspot.com/bug?extid=faba5b2419543cc95f0d
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
80fee25776c2fb61e74c1ecb1a523375c2500b69)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+faba5b2419543cc95f0d@xxxxxxxxxxxxxxxxxxxxxxxxx

divide error: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 21464 Comm: syz-executor.0 Not tainted 5.3.0-rc4 #73
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:read_super_block+0x57/0x7f0 fs/reiserfs/super.c:1611
Code: 89 d8 48 c1 e8 03 48 89 45 c0 42 80 3c 30 00 74 08 48 89 df e8 0a 29  
c5 ff 48 89 5d c8 49 8b 5f 18 4c 89 65 b8 4c 89 e0 31 d2 <48> f7 f3 49 89  
c6 4d 8d a7 28 01 00 00 4d 89 e5 49 c1 ed 03 48 b8
RSP: 0018:ffff88808e2dfa80 EFLAGS: 00010246
RAX: 0000000000002000 RBX: 0000000000000000 RCX: 0000000000040000
RDX: 0000000000000000 RSI: 0000000000003ab0 RDI: 0000000000003ab1
RBP: ffff88808e2dfad0 R08: ffffffff81e7119b R09: ffffed1011c5bf50
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000002000
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff88807a5a0a80
FS:  00007f55a9f77700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000758080 CR3: 00000000a4e4a000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 reiserfs_fill_super+0x7b0/0x30d0 fs/reiserfs/super.c:1966
 mount_bdev+0x27c/0x390 fs/super.c:1283
 get_super_block+0x34/0x40 fs/reiserfs/super.c:2599
 legacy_get_tree+0xf9/0x1a0 fs/fs_context.c:661
 vfs_get_tree+0x8f/0x380 fs/super.c:1413
 do_new_mount fs/namespace.c:2791 [inline]
 do_mount+0x169d/0x2490 fs/namespace.c:3111
 ksys_mount+0xcc/0x100 fs/namespace.c:3320
 __do_sys_mount fs/namespace.c:3334 [inline]
 __se_sys_mount fs/namespace.c:3331 [inline]
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3331
 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f55a9f76c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459829
RDX: 0000000020000080 RSI: 0000000020000100 RDI: 0000000020000040
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f55a9f776d4
R13: 00000000004c5e57 R14: 00000000004da858 R15: 00000000ffffffff
Modules linked in:
---[ end trace b618cfac8e6036db ]---
RIP: 0010:read_super_block+0x57/0x7f0 fs/reiserfs/super.c:1611
Code: 89 d8 48 c1 e8 03 48 89 45 c0 42 80 3c 30 00 74 08 48 89 df e8 0a 29  
c5 ff 48 89 5d c8 49 8b 5f 18 4c 89 65 b8 4c 89 e0 31 d2 <48> f7 f3 49 89  
c6 4d 8d a7 28 01 00 00 4d 89 e5 49 c1 ed 03 48 b8
RSP: 0018:ffff88808e2dfa80 EFLAGS: 00010246
RAX: 0000000000002000 RBX: 0000000000000000 RCX: 0000000000040000
RDX: 0000000000000000 RSI: 0000000000003ab0 RDI: 0000000000003ab1
RBP: ffff88808e2dfad0 R08: ffffffff81e7119b R09: ffffed1011c5bf50
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000002000
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff88807a5a0a80
FS:  00007f55a9f77700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcdcc16f3c CR3: 00000000a4e4a000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600


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