[PATCH v3] drm/amdgpu: Fix the memory allocation issue in amdgpu_discovery_get_nps_info()

[PATCH v3] drm/amdgpu: Fix the memory allocation issue in amdgpu_discovery_get_nps_info()

[Li Huafei]

Fix two issues with memory allocation in amdgpu_discovery_get_nps_info()
for mem_ranges:

 - Add a check for allocation failure to avoid dereferencing a null
   pointer.

 - As suggested by Christophe, use kvcalloc() for memory allocation,
   which checks for multiplication overflow.

Additionally, assign the output parameters nps_type and range_cnt after
the kvcalloc() call to prevent modifying the output parameters in case
of an error return.

Fixes: b194d21b9bcc ("drm/amdgpu: Use NPS ranges from discovery table")
Suggested-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
---
Changes in v3: 
 - As suggested by Christophe, replace kvzalloc() with kvcalloc()
 - Link to v2: https://lore.kernel.org/lkml/20241029101839.2605713-1-lihuafei1@huawei.com/

Changes in v2:
 - kvzalloc() call uses 'nps_info->v1.count' instead of '*range_cnt'
 - Link to v1: https://lore.kernel.org/lkml/20241028215933.2599271-1-lihuafei1@huawei.com/
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
index 4bd61c169ca8..620090f092ab 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
@@ -1757,11 +1757,13 @@ int amdgpu_discovery_get_nps_info(struct amdgpu_device *adev,
 
 	switch (le16_to_cpu(nps_info->v1.header.version_major)) {
 	case 1:
+		mem_ranges = kvcalloc(nps_info->v1.count,
+				      sizeof(struct amdgpu_gmc_memrange),
+				      GFP_KERNEL);
+		if (!mem_ranges)
+			return -ENOMEM;
 		*nps_type = nps_info->v1.nps_type;
 		*range_cnt = nps_info->v1.count;
-		mem_ranges = kvzalloc(
-			*range_cnt * sizeof(struct amdgpu_gmc_memrange),
-			GFP_KERNEL);
 		for (i = 0; i < *range_cnt; i++) {
 			mem_ranges[i].base_address =
 				nps_info->v1.instance_info[i].base_address;
-- 
2.25.1

Re: [PATCH v3] drm/amdgpu: Fix the memory allocation issue in amdgpu_discovery_get_nps_info()

[Alex Deucher]

On Tue, Oct 29, 2024 at 8:53 AM Li Huafei <lihuafei1@huawei.com> wrote:
>
> Fix two issues with memory allocation in amdgpu_discovery_get_nps_info()
> for mem_ranges:
>
>  - Add a check for allocation failure to avoid dereferencing a null
>    pointer.
>
>  - As suggested by Christophe, use kvcalloc() for memory allocation,
>    which checks for multiplication overflow.
>
> Additionally, assign the output parameters nps_type and range_cnt after
> the kvcalloc() call to prevent modifying the output parameters in case
> of an error return.
>
> Fixes: b194d21b9bcc ("drm/amdgpu: Use NPS ranges from discovery table")
> Suggested-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
> Signed-off-by: Li Huafei <lihuafei1@huawei.com>
> ---
> Changes in v3:
>  - As suggested by Christophe, replace kvzalloc() with kvcalloc()
>  - Link to v2: https://lore.kernel.org/lkml/20241029101839.2605713-1-lihuafei1@huawei.com/
>
> Changes in v2:
>  - kvzalloc() call uses 'nps_info->v1.count' instead of '*range_cnt'
>  - Link to v1: https://lore.kernel.org/lkml/20241028215933.2599271-1-lihuafei1@huawei.com/

Applied.  Thanks!

Alex

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
> index 4bd61c169ca8..620090f092ab 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
> @@ -1757,11 +1757,13 @@ int amdgpu_discovery_get_nps_info(struct amdgpu_device *adev,
>
>         switch (le16_to_cpu(nps_info->v1.header.version_major)) {
>         case 1:
> +               mem_ranges = kvcalloc(nps_info->v1.count,
> +                                     sizeof(struct amdgpu_gmc_memrange),
> +                                     GFP_KERNEL);
> +               if (!mem_ranges)
> +                       return -ENOMEM;
>                 *nps_type = nps_info->v1.nps_type;
>                 *range_cnt = nps_info->v1.count;
> -               mem_ranges = kvzalloc(
> -                       *range_cnt * sizeof(struct amdgpu_gmc_memrange),
> -                       GFP_KERNEL);
>                 for (i = 0; i < *range_cnt; i++) {
>                         mem_ranges[i].base_address =
>                                 nps_info->v1.instance_info[i].base_address;
> --
> 2.25.1
>

Re: [PATCH v3] drm/amdgpu: Fix the memory allocation issue in amdgpu_discovery_get_nps_info()

[Markus Elfring]

…
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
> @@ -1757,11 +1757,13 @@ int amdgpu_discovery_get_nps_info(struct amdgpu_device *adev,
>
>  	switch (le16_to_cpu(nps_info->v1.header.version_major)) {
>  	case 1:
> +		mem_ranges = kvcalloc(nps_info->v1.count,
> +				      sizeof(struct amdgpu_gmc_memrange),
> +				      GFP_KERNEL);
…

Can the specification “sizeof(*mem_ranges)” be more appropriate here?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v6.12-rc5#n941

Regards,
Markus