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Message-ID: <7c0cb998-d714-235e-8c2b-efe0315eed7f@windriver.com>
Date:   Wed, 4 Jan 2023 20:05:57 +0200
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Subject: Re: [PATCH 4.19 1/1] drm/amdkfd: Check for null pointer after calling
 kmemdup
To:     Greg KH <gregkh@linuxfoundation.org>,
        Alex Deucher <alexdeucher@gmail.com>
Cc:     =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Oded Gabbay <oded.gabbay@gmail.com>,
        David Zhou <David1.Zhou@amd.com>,
        amd-gfx@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
        Felix Kuehling <Felix.Kuehling@amd.com>,
        Jiasheng Jiang <jiasheng@iscas.ac.cn>,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        dri-devel@lists.freedesktop.org,
        Alex Deucher <alexander.deucher@amd.com>
References: <20230103184308.511448-1-dragos.panait@windriver.com>
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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

Dragos