Re: [PATCH] dma-buf: Replace strlcpy() with strscpy()

[Christian König]

Am 17.11.23 um 19:50 schrieb T.J. Mercier:
> On Thu, Nov 16, 2023 at 11:14 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> > strlcpy() reads the entire source buffer first. This read may exceed
> > the destination size limit. This is both inefficient and can lead
> > to linear read overflows if a source string is not NUL-terminated[1].
> > Additionally, it returns the size of the source string, not the
> > resulting size of the destination string. In an effort to remove strlcpy()
> > completely[2], replace strlcpy() here with strscpy().
> >
> > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1]
> > Link: https://github.com/KSPP/linux/issues/89 [2]
> > Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> > Cc: "Christian König" <christian.koenig@xxxxxxx>
> > Cc: Azeem Shaikh <azeemshaikh38@xxxxxxxxx>
> > Cc: linux-media@xxxxxxxxxxxxxxx
> > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx
> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Reviewed-by: T.J. Mercier <tjmercier@xxxxxxxxxx>
>
> strscpy returns -E2BIG when it truncates / force null-terminates which
> would provide the wrong argument for dynamic_dname, but
> dma_buf_set_name{_user} makes sure we have a null-terminated string of
> the appropriate maximum size in dmabuf->name.

Thanks for that background check, I was about to note that this might 
not be a good idea.

Linus pretty clearly stated that he doesn't want to see patches like 
that one here, see this article as well. https://lwn.net/Articles/659214/

I think the commit message gives enough reason to merge the patch, so 
I'm going to push it to drm-misc-next. But please make sure to triple 
check stuff like this before sending.

Thanks,
Christian.