[syzbot] [hfs?] kernel BUG in hfs_show_options

[syzbot] [hfs?] kernel BUG in hfs_show_options

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    aeba456828b4 Add linux-next specific files for 20230718
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1615a7b6a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e7ec534f91cfce6c
dashboard link: https://syzkaller.appspot.com/bug?extid=155274e882dcbf9885df
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=136fa2aaa80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16629fe4a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/94f67a948e1d/disk-aeba4568.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9818a252eddd/vmlinux-aeba4568.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fbf9befe9bc9/bzImage-aeba4568.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f676b00757fa/mount_1.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+155274e882dcbf9885df@syzkaller.appspotmail.com

memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=5030 'syz-executor221'
loop0: detected capacity change from 0 to 64
detected buffer overflow in strnlen
------------[ cut here ]------------
kernel BUG at lib/string_helpers.c:1031!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 5030 Comm: syz-executor221 Not tainted 6.5.0-rc2-next-20230718-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
RIP: 0010:fortify_panic+0x1c/0x20 lib/string_helpers.c:1031
Code: ba fd eb d7 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 53 48 89 fb e8 23 de 65 fd 48 89 de 48 c7 c7 00 2c c8 8a e8 e4 28 49 fd <0f> 0b 66 90 f3 0f 1e fa 41 55 41 54 55 53 48 89 fb e8 fe dd 65 fd
RSP: 0018:ffffc90003b0fb38 EFLAGS: 00010286
RAX: 0000000000000023 RBX: ffffffff8a879260 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff816aad20 RDI: 0000000000000005
RBP: ffff888029e9f000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000001 R12: 1ffff92000761f69
R13: 0000000000000004 R14: ffff88807ea07864 R15: ffffc90003b0fb68
FS:  00005555558f2380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005fdeb8 CR3: 0000000023140000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 strnlen include/linux/fortify-string.h:181 [inline]
 strscpy include/linux/fortify-string.h:324 [inline]
 hfs_show_options+0x6c7/0x7a0 fs/hfs/super.c:138
 show_vfsmnt+0x364/0x470 fs/proc_namespace.c:129
 seq_read_iter+0xaf0/0x1280 fs/seq_file.c:272
 call_read_iter include/linux/fs.h:1911 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x4e0/0x930 fs/read_write.c:470
 ksys_read+0x12f/0x250 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcba03d9ab9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd12ef40b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcba03d9ab9
RDX: 0000000000002020 RSI: 0000000020000340 RDI: 0000000000000004
RBP: 00007ffd12ef40c0 R08: 0000000000000000 R09: 65732f636f72702f
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffd12ef4308 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:fortify_panic+0x1c/0x20 lib/string_helpers.c:1031
Code: ba fd eb d7 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 53 48 89 fb e8 23 de 65 fd 48 89 de 48 c7 c7 00 2c c8 8a e8 e4 28 49 fd <0f> 0b 66 90 f3 0f 1e fa 41 55 41 54 55 53 48 89 fb e8 fe dd 65 fd
RSP: 0018:ffffc90003b0fb38 EFLAGS: 00010286
RAX: 0000000000000023 RBX: ffffffff8a879260 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff816aad20 RDI: 0000000000000005
RBP: ffff888029e9f000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000001 R12: 1ffff92000761f69
R13: 0000000000000004 R14: ffff88807ea07864 R15: ffffc90003b0fb68
FS:  00005555558f2380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005fdeb8 CR3: 0000000023140000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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Re: [syzbot] [hfs?] kernel BUG in hfs_show_options

[syzbot]

syzbot has bisected this issue to:

commit c30417b20f4993e49406f3f6d986355c6e943aa2
Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date:   Mon Jul 17 09:33:32 2023 +0000

    seq_file: Replace strncpy()+nul by strscpy()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1009eda7a80000
start commit:   aeba456828b4 Add linux-next specific files for 20230718
git tree:       linux-next
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1209eda7a80000
console output: https://syzkaller.appspot.com/x/log.txt?x=1409eda7a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e7ec534f91cfce6c
dashboard link: https://syzkaller.appspot.com/bug?extid=155274e882dcbf9885df
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=136fa2aaa80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16629fe4a80000

Reported-by: syzbot+155274e882dcbf9885df@syzkaller.appspotmail.com
Fixes: c30417b20f49 ("seq_file: Replace strncpy()+nul by strscpy()")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [syzbot] [hfs?] kernel BUG in hfs_show_options

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+155274e882dcbf9885df@syzkaller.appspotmail.com

Tested on:

commit:         aeba4568 Add linux-next specific files for 20230718
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=12db078aa80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e7ec534f91cfce6c
dashboard link: https://syzkaller.appspot.com/bug?extid=155274e882dcbf9885df
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=158d50bea80000

Note: testing is done by a robot and is best-effort only.