linux-kernel - Re: [PATCH] Staging: drivers/gpu/drm/amd/amdgpu: Fix null pointer deference in amdkfd_fence_get_timeline

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Message-ID: <ac13994c-b77b-48f2-b2cf-20299f02c2e8@amd.com>
Date: Fri, 20 Sep 2024 12:16:18 +0200
From: Christian König <christian.koenig@....com>
To: Dipendra Khadka <kdipendra88@...il.com>, Felix.Kuehling@....com,
 alexander.deucher@....com, Xinhui.Pan@....com, airlied@...il.com,
 daniel@...ll.ch
Cc: amd-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Staging: drivers/gpu/drm/amd/amdgpu: Fix null pointer
 deference in amdkfd_fence_get_timeline_name

Am 20.09.24 um 11:09 schrieb Dipendra Khadka:
> '''
> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c:108:9: error: Null pointer dereference: fence [nullPointer]
>   return fence->timeline_name;
>          ^
> '''
>
> The method to_amdgpu_amdkfd_fence can return NULL incase of empty f
> or f->ops != &amdkfd_fence_ops.Hence, check has been added .
> If fence is null , then null is returned.

Well NAK, completely nonsense. Calling the function with a NULL fence is 
illegal.

Regards,
Christian.

>
> Signed-off-by: Dipendra Khadka <kdipendra88@...il.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> index 1ef758ac5076..2313babcc944 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> @@ -105,6 +105,9 @@ static const char *amdkfd_fence_get_timeline_name(struct dma_fence *f)
>   {
>   	struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
>   
> +	if (!fence)
> +		return NULL;
> +
>   	return fence->timeline_name;
>   }
>