Re: [PATCH] cifs: Fix buffer overflow when parsing NFS reparse points

["Pali Rohár" <pali@kernel.org>]

On Monday 25 November 2024 09:54:02 Mahmoud Adam wrote:
> Pali Rohár <pali@kernel.org> writes:
> 
> > On Friday 22 November 2024 14:44:10 Mahmoud Adam wrote:
> >> From: Pali Rohár <pali@kernel.org>
> >> 
> >> upstream e2a8910af01653c1c268984855629d71fb81f404 commit.
> >> 
> >> ReparseDataLength is sum of the InodeType size and DataBuffer size.
> >> So to get DataBuffer size it is needed to subtract InodeType's size from
> >> ReparseDataLength.
> >> 
> >> Function cifs_strndup_from_utf16() is currentlly accessing buf->DataBuffer
> >> at position after the end of the buffer because it does not subtract
> >> InodeType size from the length. Fix this problem and correctly subtract
> >> variable len.
> >> 
> >> Member InodeType is present only when reparse buffer is large enough. Check
> >> for ReparseDataLength before accessing InodeType to prevent another invalid
> >> memory access.
> >> 
> >> Major and minor rdev values are present also only when reparse buffer is
> >> large enough. Check for reparse buffer size before calling reparse_mkdev().
> >> 
> >> Fixes: d5ecebc4900d ("smb3: Allow query of symlinks stored as reparse points")
> >> Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
> >> Signed-off-by: Pali Rohár <pali@kernel.org>
> >> Signed-off-by: Steve French <stfrench@microsoft.com>
> >> [use variable name symlink_buf, the other buf->InodeType accesses are
> >> not used in current version so skip]
> >> Signed-off-by: Mahmoud Adam <mngyadam@amazon.com>
> >> ---
> >> This fixes CVE-2024-49996, and applies cleanly on 5.4->6.1, 6.6 and
> >> later already has the fix.
> >
> > Interesting... I have not know that there is CVE number for this issue.
> > Have you asked for assigning CVE number? Or was it there before?
> >
> Nope, It was assigned a CVE here:
>  https://lore.kernel.org/all/2024102138-CVE-2024-49996-0d29@gregkh/
> 
> -MNAdam

I did not know that somebody already assigned it there.
It would be nice in future to inform people involved in the change about
assigning CVE number for the change.