Re: [PATCH 1/5] drm/amdgpu: Move a variable assignment behind a null pointer check in amdgpu_ras_interrupt_dispatch()

[Markus Elfring <Markus.Elfring@web.de>]

> Date: Tue, 11 Apr 2023 10:52:48 +0200
>
> The address of a data structure member was determined before
> a corresponding null pointer check in the implementation of
> the function “amdgpu_ras_interrupt_dispatch”.
>
> Thus avoid the risk for undefined behaviour by moving the assignment
> for the variable “data” behind the null pointer check.
>
> This issue was detected by using the Coccinelle software.
>
> Fixes: c030f2e4166c3f5597c7e7a70bcd9ab383695de4 ("drm/amdgpu: add amdgpu_ras.c to support ras (v2)")
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> index 4069bce9479f..a920c7888d07 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> @@ -1730,11 +1730,12 @@ int amdgpu_ras_interrupt_dispatch(struct amdgpu_device *adev,
>  		struct ras_dispatch_if *info)
>  {
>  	struct ras_manager *obj = amdgpu_ras_find_obj(adev, &info->head);
> -	struct ras_ih_data *data = &obj->ih_data;
> +	struct ras_ih_data *data;
>
>  	if (!obj)
>  		return -EINVAL;
>
> +	data = &obj->ih_data;
>  	if (data->inuse == 0)
>  		return 0;
>

I would like to point out that another software adjustment got the desired
development attention (on 2024-05-11).

See also:
Commit 4c11d30c95576937c6c35e6f29884761f2dddb43 ("drm/amdgpu:
Fix the null pointer dereference to ras_manager")

Regards,
Markus