linux-kernel - [syzbot] [bcachefs?] divide error in __bch2

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Message-ID: <66ec9a7d.050a0220.29194.004a.GAE@google.com>
Date: Thu, 19 Sep 2024 14:41:17 -0700
From: syzbot <syzbot+24beef64217854da05a4@...kaller.appspotmail.com>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bcachefs?] divide error in __bch2_strtoh

Hello,

syzbot found the following issue on:

HEAD commit:    932d2d1fcb2b Merge tag 'dlm-6.12' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=157b3b00580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c208b3605ba9ec44
dashboard link: https://syzkaller.appspot.com/bug?extid=24beef64217854da05a4
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11bf0ca9980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14d26607980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-932d2d1f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fbcb7198214b/vmlinux-932d2d1f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/418eaebf4817/bzImage-932d2d1f.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/dd062a95a35e/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+24beef64217854da05a4@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
Oops: divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5102 Comm: syz-executor109 Not tainted 6.11.0-syzkaller-05442-g932d2d1fcb2b #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:div_u64_rem include/linux/math64.h:29 [inline]
RIP: 0010:div_u64 include/linux/math64.h:130 [inline]
RIP: 0010:__bch2_strtou64_h fs/bcachefs/util.c:143 [inline]
RIP: 0010:__bch2_strtoh+0xb59/0xeb0 fs/bcachefs/util.c:168
Code: ff 0f 88 8f 00 00 00 4c 89 74 24 08 44 89 f8 48 01 c5 48 89 2c 24 e8 96 52 49 fd 4d 89 e6 44 89 e1 48 c7 c0 ff ff ff ff 31 d2 <48> f7 f1 48 89 c5 48 8b 5c 24 18 48 89 df 48 89 c6 e8 d1 54 49 fd
RSP: 0018:ffffc90002dff8e8 EFLAGS: 00010246
RAX: ffffffffffffffff RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffff8880382487a2 R08: ffffffff844a8c4d R09: 0000000000000000
R10: 0000000000000009 R11: ffff88801fdc8000 R12: 1000000000000000
R13: ffff8880382487a0 R14: 1000000000000000 R15: 0000000000000001
FS:  00005555730ab380(0000) GS:ffff88801fe00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9b13dff000 CR3: 000000004001a000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 bch2_strtou64_h+0xa5/0x120 fs/bcachefs/util.c:205
 bch2_opt_parse+0x2dd/0x4c0 fs/bcachefs/opts.c:353
 bch2_parse_one_mount_opt+0x2d3/0x5e0 fs/bcachefs/opts.c:501
 bch2_fs_parse_param+0x137/0x180 fs/bcachefs/fs.c:2095
 vfs_parse_fs_param+0x1a5/0x420 fs/fs_context.c:146
 vfs_parse_fs_string fs/fs_context.c:188 [inline]
 vfs_parse_monolithic_sep fs/fs_context.c:230 [inline]
 generic_parse_monolithic+0x2c8/0x400 fs/fs_context.c:258
 do_new_mount+0x28f/0xb40 fs/namespace.c:3503
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4055 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4032
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9b1b2ffdea
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffef7660ac8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffef7660ae0 RCX: 00007f9b1b2ffdea
RDX: 0000000020000040 RSI: 000000002000f680 RDI: 00007ffef7660ae0
RBP: 0000000000000004 R08: 00007ffef7660b20 R09: 000000000000f62d
R10: 0000000000000000 R11: 0000000000000282 R12: 0000000000000000
R13: 00007ffef7660b20 R14: 0000000000000003 R15: 0000000001000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:div_u64_rem include/linux/math64.h:29 [inline]
RIP: 0010:div_u64 include/linux/math64.h:130 [inline]
RIP: 0010:__bch2_strtou64_h fs/bcachefs/util.c:143 [inline]
RIP: 0010:__bch2_strtoh+0xb59/0xeb0 fs/bcachefs/util.c:168
Code: ff 0f 88 8f 00 00 00 4c 89 74 24 08 44 89 f8 48 01 c5 48 89 2c 24 e8 96 52 49 fd 4d 89 e6 44 89 e1 48 c7 c0 ff ff ff ff 31 d2 <48> f7 f1 48 89 c5 48 8b 5c 24 18 48 89 df 48 89 c6 e8 d1 54 49 fd
RSP: 0018:ffffc90002dff8e8 EFLAGS: 00010246
RAX: ffffffffffffffff RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffff8880382487a2 R08: ffffffff844a8c4d R09: 0000000000000000
R10: 0000000000000009 R11: ffff88801fdc8000 R12: 1000000000000000
R13: ffff8880382487a0 R14: 1000000000000000 R15: 0000000000000001
FS:  00005555730ab380(0000) GS:ffff88801fe00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b9811eb7f8 CR3: 000000004001a000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	ff 0f                	decl   (%rdi)
   2:	88 8f 00 00 00 4c    	mov    %cl,0x4c000000(%rdi)
   8:	89 74 24 08          	mov    %esi,0x8(%rsp)
   c:	44 89 f8             	mov    %r15d,%eax
   f:	48 01 c5             	add    %rax,%rbp
  12:	48 89 2c 24          	mov    %rbp,(%rsp)
  16:	e8 96 52 49 fd       	call   0xfd4952b1
  1b:	4d 89 e6             	mov    %r12,%r14
  1e:	44 89 e1             	mov    %r12d,%ecx
  21:	48 c7 c0 ff ff ff ff 	mov    $0xffffffffffffffff,%rax
  28:	31 d2                	xor    %edx,%edx
* 2a:	48 f7 f1             	div    %rcx <-- trapping instruction
  2d:	48 89 c5             	mov    %rax,%rbp
  30:	48 8b 5c 24 18       	mov    0x18(%rsp),%rbx
  35:	48 89 df             	mov    %rbx,%rdi
  38:	48 89 c6             	mov    %rax,%rsi
  3b:	e8 d1 54 49 fd       	call   0xfd495511


---
This report is generated by a bot. It may contain errors.
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