[PATCH] drm/amdgpu: ensure device_list is initialised before calling list_add_tail

[PATCH] drm/amdgpu: ensure device_list is initialised before calling list_add_tail

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Currently the call to list_add_tail will access an the uninitalised
device_list.prev. Fix this by ensuring device_list is initialized before
adding items to it.

Addresses-Coverity: ("Uninitialized pointer read")
Fixes: b3dbd6d3ec49 ("drm/amdgpu: resolve mGPU RAS query instability")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
index b0aa4e1ed4df..caa4969bd46f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
@@ -1447,6 +1447,7 @@ static void amdgpu_ras_do_recovery(struct work_struct *work)
 	if  (hive && adev->gmc.xgmi.num_physical_nodes > 1) {
 		device_list_handle = &hive->device_list;
 	} else {
+		INIT_LIST_HEAD(&device_list);
 		list_add_tail(&adev->gmc.xgmi.head, &device_list);
 		device_list_handle = &device_list;
 	}
-- 
2.25.1

Re: [PATCH] drm/amdgpu: ensure device_list is initialised before calling list_add_tail

[Andrey Grodzovsky]

On 4/10/20 6:57 PM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Currently the call to list_add_tail will access an the uninitalised
> device_list.prev. Fix this by ensuring device_list is initialized before
> adding items to it.
>
> Addresses-Coverity: ("Uninitialized pointer read")


That weird, I see that his is already initialized unconditionally here - 
https://elixir.bootlin.com/linux/v5.6.3/source/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c#L4022

Andrey


> Fixes: b3dbd6d3ec49 ("drm/amdgpu: resolve mGPU RAS query instability")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> index b0aa4e1ed4df..caa4969bd46f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> @@ -1447,6 +1447,7 @@ static void amdgpu_ras_do_recovery(struct work_struct *work)
>   	if  (hive && adev->gmc.xgmi.num_physical_nodes > 1) {
>   		device_list_handle = &hive->device_list;
>   	} else {
> +		INIT_LIST_HEAD(&device_list);
>   		list_add_tail(&adev->gmc.xgmi.head, &device_list);
>   		device_list_handle = &device_list;
>   	}