[PATCH] drm/amdgpu: Fix buffer size to prevent truncation in gfx_v12_0_init_microcode

[Lazar, Lijo]

On 5/7/2024 10:14 PM, Srinivasan Shanmugam wrote:
> This commit addresses multiple warnings in the gfx_v12_0_init_microcode
> function in the gfx_v12_0.c file. The warnings were related to potential
> truncation when writing the strings _pfp.bin, _me.bin, _rlc.bin, and
> _mec.bin into the fw_name buffer.
> 
> This commit fixes multiple potential truncations when writing the
> strings _pfp.bin, _me.bin, _rlc.bin, and _mec.bin into the fw_name
> buffer in the gfx_v12_0_init_microcode function in the gfx_v12_0.c file
> 
> The ucode_prefix size was reduced from 30 to 15 to ensure the snprintf
> function does not exceed the size of the fw_name buffer.
> 
> Thus fixing the below with gcc W=1:
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c: In function ‘gfx_v12_0_early_init’:
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c:421:54: warning: ‘_pfp.bin’ directive output may be truncated writing 8 bytes into a region of size between 4 and 33 [-Wformat-truncation=]
>   421 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_pfp.bin", ucode_prefix);
>       |                                                      ^~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c:421:9: note: ‘snprintf’ output between 16 and 45 bytes into a destination of size 40
>   421 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_pfp.bin", ucode_prefix);
>       |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c:428:54: warning: ‘_me.bin’ directive output may be truncated writing 7 bytes into a region of size between 4 and 33 [-Wformat-truncation=]
>   428 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_me.bin", ucode_prefix);
>       |                                                      ^~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c:428:9: note: ‘snprintf’ output between 15 and 44 bytes into a destination of size 40
>   428 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_me.bin", ucode_prefix);
>       |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c:436:62: warning: ‘_rlc.bin’ directive output may be truncated writing 8 bytes into a region of size between 4 and 33 [-Wformat-truncation=]
>   436 |                 snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_rlc.bin", ucode_prefix);
>       |                                                              ^~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c:436:17: note: ‘snprintf’ output between 16 and 45 bytes into a destination of size 40
>   436 |                 snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_rlc.bin", ucode_prefix);
>       |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c:448:54: warning: ‘_mec.bin’ directive output may be truncated writing 8 bytes into a region of size between 4 and 33 [-Wformat-truncation=]
>   448 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mec.bin", ucode_prefix);
>       |                                                      ^~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c:448:9: note: ‘snprintf’ output between 16 and 45 bytes into a destination of size 40
>   448 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mec.bin", ucode_prefix);
>       |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Cc: Lijo Lazar <lijo.lazar at amd.com>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>

Reviewed-by: Lijo Lazar <lijo.lazar at amd.com>

Thanks,
Lijo

> ---
>  drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c
> index b53ca25012e6..b6e5a2230622 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v12_0.c
> @@ -408,7 +408,7 @@ static int gfx_v12_0_init_toc_microcode(struct amdgpu_device *adev, const char *
>  static int gfx_v12_0_init_microcode(struct amdgpu_device *adev)
>  {
>  	char fw_name[40];
> -	char ucode_prefix[30];
> +	char ucode_prefix[15];
>  	int err;
>  	const struct rlc_firmware_header_v2_0 *rlc_hdr;
>  	uint16_t version_major;