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

From: Dragos-Marian Panait
Date: Wed Jan 04 2023 - 13:07:51 EST



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@xxxxxxx> 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@xxxxxxxxxxx>

[ 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@xxxxxxxxxxx>
Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Dragos-Marian Panait <dragos.panait@xxxxxxxxxxxxx>
---
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

Dragos