Re: WARNING in verify_dirent_name

[Eric Biggers]

On Mon, Oct 07, 2019 at 07:31:07AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    43b815c6 Merge tag 'armsoc-fixes' of git://git.kernel.org/..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=12165d0b600000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=1ec3be9936e004f6
> dashboard link: https://syzkaller.appspot.com/bug?extid=76e3977ad1b8cc4d113a
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> 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+76e3977ad1b8cc4d113a@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 25558 at fs/readdir.c:150 verify_dirent_name+0x67/0x80
> fs/readdir.c:150
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 1 PID: 25558 Comm: syz-executor.2 Not tainted 5.4.0-rc1+ #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x172/0x1f0 lib/dump_stack.c:113
>  panic+0x2dc/0x755 kernel/panic.c:220
>  __warn.cold+0x2f/0x3c kernel/panic.c:581
>  report_bug+0x289/0x300 lib/bug.c:195
>  fixup_bug arch/x86/kernel/traps.c:179 [inline]
>  fixup_bug arch/x86/kernel/traps.c:174 [inline]
>  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
>  do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
>  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
> RIP: 0010:verify_dirent_name+0x67/0x80 fs/readdir.c:150
> Code: 19 b6 ff 44 89 e0 5b 41 5c 5d c3 e8 43 19 b6 ff 0f 0b e8 3c 19 b6 ff
> 41 bc fb ff ff ff 5b 44 89 e0 41 5c 5d c3 e8 29 19 b6 ff <0f> 0b 41 bc fb ff
> ff ff eb ca 0f 1f 44 00 00 66 2e 0f 1f 84 00 00
> RSP: 0018:ffff88808db87ad0 EFLAGS: 00010212
> RAX: 0000000000040000 RBX: 000000000000000c RCX: ffffc900143e7000
> RDX: 0000000000004d26 RSI: ffffffff81bcf9b7 RDI: ffff88808db87cd3
> RBP: ffff88808db87ae0 R08: ffff88808f5c41c0 R09: 0000000000000004
> R10: fffffbfff120d9b8 R11: ffffffff8906cdc3 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000004 R15: ffff88808db87e50
>  filldir64+0x40/0x670 fs/readdir.c:356
>  dir_emit include/linux/fs.h:3542 [inline]
>  __fat_readdir+0xd9e/0x1cb0 fs/fat/dir.c:677
>  fat_readdir+0x44/0x60 fs/fat/dir.c:704
>  iterate_dir+0x47f/0x5e0 fs/readdir.c:105
>  ksys_getdents64+0x1ce/0x320 fs/readdir.c:412
>  __do_sys_getdents64 fs/readdir.c:431 [inline]
>  __se_sys_getdents64 fs/readdir.c:428 [inline]
>  __x64_sys_getdents64+0x73/0xb0 fs/readdir.c:428
>  do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x459a59
> 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:00007fc825c13c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459a59
> RDX: 0000000000001000 RSI: 00000000200005c0 RDI: 0000000000000007
> RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc825c146d4
> R13: 00000000004c0533 R14: 00000000004d2c58 R15: 00000000ffffffff
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
> 
> 
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
> 
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> 

#syz dup: WARNING in filldir64