Re: patch-2.7.3 no longer applies relative symbolic link patches

[David Kastrup <dak@gnu.org>]

Linus Torvalds <torvalds@linux-foundation.org> writes:

> On Mon, Jan 26, 2015 at 8:32 AM, Josh Boyer <jwboyer@fedoraproject.org> wrote:
>>
>> I went to do the Fedora 3.19-rc6 build this morning and it failed in
>> our buildsystem with:
>>
>> + '[' '!' -f /builddir/build/SOURCES/patch-3.19-rc6.xz ']'
>> + case "$patch" in
>> + unxz
>> + patch -p1 -F1 -s
>> symbolic link target '../../../../../include/dt-bindings' is invalid
>> error: Bad exit status from /var/tmp/rpm-tmp.mWE3ZL (%prep)
>
> Ugh. I don't see anything we can do about this on the git side, and I
> do kind of understand why 'patch' would be worried about '..' files.
> In a perfect world, patch would parse the filename and see that it
> stays within the directory structure of the project, but that is a
> rather harder thing to do than just say "no dot-dot files".
>
> The short-term fix is likely to just use "git apply" instead of "patch".
>
> The long-term fix? I dunno. I don't see us not using symlinks, and a
> quick check says that every *single* symlink we have in the kernel
> source tree is one that points to a different directory using ".."
> format. And while I could imagine that "patch" ends up counting the
> dot-dot entries and checking that it's all inside the same tree it is
> patching, I could also easily see patch *not* doing that.

I consider it rather hard and error-prone and/or an attack vector to
choose a course of action for ../ in connection with the -p option.

-- 
David Kastrup