[PATCH] drm/amdgpu: Fix buffer size in gfx_v9_4_3_init_ cp_compute_microcode() and rlc_microcode()

[Srinivasan Shanmugam]

The buffer size is determined by the declaration char fw_name[30]; This
means fw_name can hold up to 30 characters, including the null character
that marks the end of the string.

The string to be written is "amdgpu/%s_mec.bin" or "amdgpu/%s_rlc.bin",
where %s will be replaced by the value of chip_name.

The length of the string "amdgpu/%s_mec.bin" or "amdgpu/%s_rlc.bin"
without the %s is 16 characters.

The warning message is saying that the chip_name could be up to 29
characters long. If we add the 16 characters from the string
"amdgpu/%s_mec.bin" or "amdgpu/%s_rlc.bin", we get a total of 45
characters.

This is potentially longer than the buffer size of 30 characters.

if chip_name is longer than 14 characters (30 buffer size - 16
characters from the string), the resulting string will not fit into the
fw_name buffer, Thus increasing fw_name buffer size to 50

Fixes the below with gcc W=1:
drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c: In function ‘gfx_v9_4_3_early_init’:
drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:379:52: warning: ‘%s’ directive output may be truncated writing up to 29 bytes into a region of size 23 [-Wformat-truncation=]
  379 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_rlc.bin", chip_name);
      |                                                    ^~
......
  439 |         r = gfx_v9_4_3_init_rlc_microcode(adev, ucode_prefix);
      |                                                 ~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:379:9: note: ‘snprintf’ output between 16 and 45 bytes into a destination of size 30
  379 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_rlc.bin", chip_name);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:413:52: warning: ‘%s’ directive output may be truncated writing up to 29 bytes into a region of size 23 [-Wformat-truncation=]
  413 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mec.bin", chip_name);
      |                                                    ^~
......
  443 |         r = gfx_v9_4_3_init_cp_compute_microcode(adev, ucode_prefix);
      |                                                        ~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:413:9: note: ‘snprintf’ output between 16 and 45 bytes into a destination of size 30
  413 |         snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mec.bin", chip_name);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 86301129698b ("drm/amdgpu: split gc v9_4_3 functionality from gc v9_0")
Cc: Hawking Zhang <Hawking.Zhang at amd.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Alex Deucher <alexander.deucher at amd.com>
Cc: Lijo Lazar <lijo.lazar at amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c
index 0e429b7ed036..1c46d5f6677f 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c
@@ -370,7 +370,7 @@ static void gfx_v9_4_3_free_microcode(struct amdgpu_device *adev)
 static int gfx_v9_4_3_init_rlc_microcode(struct amdgpu_device *adev,
 					  const char *chip_name)
 {
-	char fw_name[30];
+	char fw_name[50];
 	int err;
 	const struct rlc_firmware_header_v2_0 *rlc_hdr;
 	uint16_t version_major;
@@ -407,7 +407,7 @@ static void gfx_v9_4_3_check_if_need_gfxoff(struct amdgpu_device *adev)
 static int gfx_v9_4_3_init_cp_compute_microcode(struct amdgpu_device *adev,
 					  const char *chip_name)
 {
-	char fw_name[30];
+	char fw_name[50];
 	int err;
 
 	snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mec.bin", chip_name);
-- 
2.34.1