[PATCH v2] drm/amdgpu: Fix snprintf usage in amdgpu_gfx_kiq_init_ring

[Srinivasan Shanmugam]

This commit fixes a format truncation issue arosed by the snprintf
function potentially writing more characters into the ring->name buffer
than it can hold, in the amdgpu_gfx_kiq_init_ring function 
  
The issue occurred because the '%d' format specifier could write between
1 and 10 bytes into a region of size between 0 and 8, depending on the
values of xcc_id, ring->me, ring->pipe, and ring->queue. The snprintf
function could output between 12 and 41 bytes into a destination of size
16, leading to potential truncation.  
  
To resolve this, the snprintf line was modified to use the '%hhu' format
specifier for ring->me, ring->pipe, and ring->queue. The '%hhu'
specifier is used for unsigned char variables and ensures that these
values are printed as unsigned decimal integers.

Fixes the below with gcc W=1:
drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c: In function ‘amdgpu_gfx_kiq_init_ring’:
drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c:332:61: warning: ‘%d’ directive output may be truncated writing between 1 and 10 bytes into a region of size between 0 and 8 [-Wformat-truncation=]
  332 |         snprintf(ring->name, sizeof(ring->name), "kiq_%d.%d.%d.%d",
      |                                                             ^~
drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c:332:50: note: directive argument in the range [0, 2147483647]
  332 |         snprintf(ring->name, sizeof(ring->name), "kiq_%d.%d.%d.%d",
      |                                                  ^~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c:332:9: note: ‘snprintf’ output between 12 and 41 bytes into a destination of size 16
  332 |         snprintf(ring->name, sizeof(ring->name), "kiq_%d.%d.%d.%d",
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  333 |                  xcc_id, ring->me, ring->pipe, ring->queue);
      |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 345a36c4f1ba ("drm/amdgpu: prefer snprintf over sprintf")
Cc: Alex Deucher <alexander.deucher at amd.com>
Cc: Christian König <christian.koenig at amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
---
v2:
 - Removed width specifiers %3, %1, typecasting of unsigned char,
   s/hhd/hhu (Lijo)

 drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
index 9b7dc61c331d..0f14d4a11441 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
@@ -329,7 +329,7 @@ int amdgpu_gfx_kiq_init_ring(struct amdgpu_device *adev, int xcc_id)
 
 	ring->eop_gpu_addr = kiq->eop_gpu_addr;
 	ring->no_scheduler = true;
-	snprintf(ring->name, sizeof(ring->name), "kiq_%d.%d.%d.%d",
+	snprintf(ring->name, sizeof(ring->name), "kiq_%d.%hhu.%hhu.%hhu",
 		 xcc_id, ring->me, ring->pipe, ring->queue);
 	r = amdgpu_ring_init(adev, ring, 1024, irq, AMDGPU_CP_KIQ_IRQ_DRIVER0,
 			     AMDGPU_RING_PRIO_DEFAULT, NULL);
-- 
2.34.1