linux-kernel - Re: [PATCH v2] drm/amdgpu: Use kmalloc

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Message-ID: <82fee878-929b-4373-a476-63f34122d780@amd.com>
Date: Mon, 22 Sep 2025 09:59:15 -0400
From: "Kuehling, Felix" <felix.kuehling@....com>
To: Rahul Kumar <rk0006818@...il.com>, alexander.deucher@....com,
 christian.koenig@....com, airlied@...il.com, simona@...ll.ch
Cc: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org,
 linux-kernel-mentees@...ts.linuxfoundation.org, skhan@...uxfoundation.org
Subject: Re: [PATCH v2] drm/amdgpu: Use kmalloc_array() instead of kmalloc()

On 2025-09-18 03:12, Rahul Kumar wrote:
> Documentation/process/deprecated.rst recommends against the use of
> kmalloc with dynamic size calculations due to the risk of overflow and
> smaller allocation being made than the caller was expecting.
>
> Replace kmalloc() with kmalloc_array() in amdgpu_amdkfd_gfx_v10.c,
> amdgpu_amdkfd_gfx_v10_3.c, amdgpu_amdkfd_gfx_v11.c and
> amdgpu_amdkfd_gfx_v12.c to make the intended allocation size clearer
> and avoid potential overflow issues.
>
> Suggested-by: Felix Kuehling <felix.kuehling@....com>
> Signed-off-by: Rahul Kumar <rk0006818@...il.com>

Thank you. I applied the patch to amd-staging-drm-next.

Reviewed-by: Felix Kuehling <felix.kuehling@....com>


> ---
> Changes since v1:
> - Extend fix to amdgpu_amdkfd_gfx_v10_3.c, amdgpu_amdkfd_gfx_v11.c and
>    amdgpu_amdkfd_gfx_v12.c as suggested.
> - Added Suggested-by tag.
> Link to v1:
> https://lore.kernel.org/all/f782159b-ad3f-4d0c-8476-50a701bf29e6@amd.com/
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10.c   | 4 ++--
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10_3.c | 4 ++--
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c   | 4 ++--
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v12.c   | 4 ++--
>   4 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10.c
> index 04ef0ca10541..0239114fb6c4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10.c
> @@ -352,7 +352,7 @@ static int kgd_hqd_dump(struct amdgpu_device *adev,
>   		(*dump)[i++][1] = RREG32_SOC15_IP(GC, addr);		\
>   	} while (0)
>   
> -	*dump = kmalloc(HQD_N_REGS*2*sizeof(uint32_t), GFP_KERNEL);
> +	*dump = kmalloc_array(HQD_N_REGS, sizeof(**dump), GFP_KERNEL);
>   	if (*dump == NULL)
>   		return -ENOMEM;
>   
> @@ -449,7 +449,7 @@ static int kgd_hqd_sdma_dump(struct amdgpu_device *adev,
>   #undef HQD_N_REGS
>   #define HQD_N_REGS (19+6+7+10)
>   
> -	*dump = kmalloc(HQD_N_REGS*2*sizeof(uint32_t), GFP_KERNEL);
> +	*dump = kmalloc_array(HQD_N_REGS, sizeof(**dump), GFP_KERNEL);
>   	if (*dump == NULL)
>   		return -ENOMEM;
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10_3.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10_3.c
> index 6d08bc2781a3..f2278a0937ff 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10_3.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10_3.c
> @@ -338,7 +338,7 @@ static int hqd_dump_v10_3(struct amdgpu_device *adev,
>   		(*dump)[i++][1] = RREG32_SOC15_IP(GC, addr);		\
>   	} while (0)
>   
> -	*dump = kmalloc(HQD_N_REGS*2*sizeof(uint32_t), GFP_KERNEL);
> +	*dump = kmalloc_array(HQD_N_REGS, sizeof(**dump), GFP_KERNEL);
>   	if (*dump == NULL)
>   		return -ENOMEM;
>   
> @@ -435,7 +435,7 @@ static int hqd_sdma_dump_v10_3(struct amdgpu_device *adev,
>   #undef HQD_N_REGS
>   #define HQD_N_REGS (19+6+7+12)
>   
> -	*dump = kmalloc(HQD_N_REGS*2*sizeof(uint32_t), GFP_KERNEL);
> +	*dump = kmalloc_array(HQD_N_REGS, sizeof(**dump), GFP_KERNEL);
>   	if (*dump == NULL)
>   		return -ENOMEM;
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c
> index e0e6a6a49d90..aaccf0b9947d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c
> @@ -323,7 +323,7 @@ static int hqd_dump_v11(struct amdgpu_device *adev,
>   		(*dump)[i++][1] = RREG32(addr);		\
>   	} while (0)
>   
> -	*dump = kmalloc(HQD_N_REGS*2*sizeof(uint32_t), GFP_KERNEL);
> +	*dump = kmalloc_array(HQD_N_REGS, sizeof(**dump), GFP_KERNEL);
>   	if (*dump == NULL)
>   		return -ENOMEM;
>   
> @@ -420,7 +420,7 @@ static int hqd_sdma_dump_v11(struct amdgpu_device *adev,
>   #undef HQD_N_REGS
>   #define HQD_N_REGS (7+11+1+12+12)
>   
> -	*dump = kmalloc(HQD_N_REGS*2*sizeof(uint32_t), GFP_KERNEL);
> +	*dump = kmalloc_array(HQD_N_REGS, sizeof(**dump), GFP_KERNEL);
>   	if (*dump == NULL)
>   		return -ENOMEM;
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v12.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v12.c
> index 6f0dc23c901b..e0ceab400b2d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v12.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v12.c
> @@ -115,7 +115,7 @@ static int hqd_dump_v12(struct amdgpu_device *adev,
>   		(*dump)[i++][1] = RREG32(addr);		\
>   	} while (0)
>   
> -	*dump = kmalloc(HQD_N_REGS*2*sizeof(uint32_t), GFP_KERNEL);
> +	*dump = kmalloc_array(HQD_N_REGS, sizeof(**dump), GFP_KERNEL);
>   	if (*dump == NULL)
>   		return -ENOMEM;
>   
> @@ -146,7 +146,7 @@ static int hqd_sdma_dump_v12(struct amdgpu_device *adev,
>   #undef HQD_N_REGS
>   #define HQD_N_REGS (last_reg - first_reg + 1)
>   
> -	*dump = kmalloc(HQD_N_REGS*2*sizeof(uint32_t), GFP_KERNEL);
> +	*dump = kmalloc_array(HQD_N_REGS, sizeof(**dump), GFP_KERNEL);
>   	if (*dump == NULL)
>   		return -ENOMEM;
>