Re: [PATCH 4.19 1/1] drm/amdkfd: Check for null pointer after calling kmemdup

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Jan 04, 2023 at 08:05:57PM +0200, Dragos-Marian Panait wrote:
> 
> On 04.01.2023 16:48, Greg KH wrote:
> > On Wed, Jan 04, 2023 at 09:35:03AM -0500, Alex Deucher wrote:
> > > On Wed, Jan 4, 2023 at 8:23 AM Christian König <christian.koenig@amd.com> wrote:
> > > > Am 04.01.23 um 13:41 schrieb Greg KH:
> > > > > On Tue, Jan 03, 2023 at 08:43:08PM +0200, Dragos-Marian Panait wrote:
> > > > > > From: Jiasheng Jiang <jiasheng@iscas.ac.cn>
> > > > > > 
> > > > > > [ Upstream commit abfaf0eee97925905e742aa3b0b72e04a918fa9e ]
> > > > > > 
> > > > > > As the possible failure of the allocation, kmemdup() may return NULL
> > > > > > pointer.
> > > > > > Therefore, it should be better to check the 'props2' in order to prevent
> > > > > > the dereference of NULL pointer.
> > > > > > 
> > > > > > Fixes: 3a87177eb141 ("drm/amdkfd: Add topology support for dGPUs")
> > > > > > Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
> > > > > > Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
> > > > > > Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
> > > > > > Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> > > > > > Signed-off-by: Dragos-Marian Panait <dragos.panait@windriver.com>
> > > > > > ---
> > > > > >    drivers/gpu/drm/amd/amdkfd/kfd_crat.c | 3 +++
> > > > > >    1 file changed, 3 insertions(+)
> > > > > For obvious reasons, I can't take a patch for 4.19.y and not newer
> > > > > kernel releases, right?
> > > > > 
> > > > > Please provide backports for all kernels if you really need to see this
> > > > > merged.  And note, it's not a real bug at all, and given that a CVE was
> > > > > allocated for it that makes me want to even more reject it to show the
> > > > > whole folly of that mess.
> > > > Well as far as I can see this is nonsense to back port.
> > > > 
> > > > The code in question is only used only once during driver load and then
> > > > never again, that exactly this allocation fails while tons of other are
> > > > made before and after is extremely unlikely.
> > > > 
> > > > It's nice to have it fixed in newer kernels, but not worth a backport
> > > > and certainly not stuff for a CVE.
> > > It's already fixed in Linus' tree:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=abfaf0eee97925905e742aa3b0b72e04a918fa9e
> > Yes, that's what the above commit shows...
> > 
> > confused,
> > 
> > greg k-h
> Just for completeness, I also sent out patches for 5.4 and 5.10 stable
> branches.
> 5.15 stable branch already has this change: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.15.y&id=5609b7803947eea1711516dd8659c7ed39f5a868

Again, this is not a real bug and someone needs to go and invalidate
that CVE so you don't have to worry about it anymore.  I suggest that
you do that if your company cares about tracking CVEs.

thanks,

greg k-h