Re: [PATCH] ntfs: Fix validity check for file name attribute

[Desmond Cheong Zhi Xi]

On 29/7/21 4:31 pm, Rolf Eike Beer wrote:
> Hi,
>
> I was just scanning through some older vulnerabilities and came across
> CVE-2018-12929, CVE-2018-12930, and CVE-2018-12931, which are all still open
> according to linuxkernelcves.com (originally reported against 4.15 [1]). I
> looked into the commits in fs/ntfs/ from 4.15 onwards to see if they were just
> missed, but I can't spot anything there. RedHat claims to have them fixed in
> one of their kernels [2].
>
> Which makes me wonder if the issue fixed here is a duplicate of the any of the
> above. Is there a reason I can't find any patches for the original issue in
> tree, like the issue only introduced in a custom patchset that Ubuntu/RedHat
> were using? Is this thing worth it's own CVE if it's no duplicate?
>
> Greetings,
>
> Eike
>
> 1) https://marc.info/?t=152407734400002&r=1&w=2
> 2) https://access.redhat.com/errata/RHSA-2019:0641

Hi Eike,

Thanks for digging into this. From a first glance, this bug seems most 
similar to CVE-2018-12929.

However, from the logs, the root causes are probably different. The 
cause of this bug is specifically in the call to 
ntfs_is_extended_system_file [1], but from what I can see this is not 
the case for CVE-2018-12929. I don't know enough to comment whether it 
needs a CVE, but it has been patched on Linux stable (up to 4.4).

It's worth noting that there's another similar bug that was fixed by 
Rustam Kovhaev (+cc) in ntfs_read_locked_inode [2]. This may or may not 
have been the issue in CVE-2018-12929.

Link: 
https://syzkaller.appspot.com/bug?id=a1a1e379b225812688566745c3e2f7242bffc246 
[1]

Link: 
https://syzkaller.appspot.com/bug?id=933dab9c03ac47a3d09dd4b0563a0a8fcb35f282 
[2]

Best wishes,
Desmond