drm/msm: fix missing NULL check after kcalloc in crashstate_get_bos()

The crashstate_get_bos() function allocates memory for `state->bos`
using kcalloc(), but the vmbind path does not check for allocation
failure before dereferencing it in the following drm_gpuvm_for_each_va()
loop. This could lead to a NULL pointer dereference if memory allocation
fails.

Fix this by wrapping the drm_gpuvm_for_each_va() loop with a NULL check
on state->bos, similar to the safety check in the non-vmbind path.

Fixes: af9aa6f ("drm/msm: Crashdump support for sparse")
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Patchwork: https://patchwork.freedesktop.org/patch/687556/
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>

Author: haryven

drivers/gpu/drm/msm/msm_gpu.c

@@ -287,16 +287,17 @@ static void crashstate_get_bos(struct msm_gpu_state *state, struct msm_gem_submi
 
 		state->bos = kcalloc(cnt, sizeof(struct msm_gpu_state_bo), GFP_KERNEL);
 
-		drm_gpuvm_for_each_va (vma, submit->vm) {
-			bool dump = rd_full || (vma->flags & MSM_VMA_DUMP);
+		if (state->bos)
+			drm_gpuvm_for_each_va(vma, submit->vm) {
+				bool dump = rd_full || (vma->flags & MSM_VMA_DUMP);
 
-			/* Skip MAP_NULL/PRR VMAs: */
-			if (!vma->gem.obj)
-				continue;
+				/* Skip MAP_NULL/PRR VMAs: */
+				if (!vma->gem.obj)
+					continue;
 
-			msm_gpu_crashstate_get_bo(state, vma->gem.obj, vma->va.addr,
-						  dump, vma->gem.offset, vma->va.range);
-		}
+				msm_gpu_crashstate_get_bo(state, vma->gem.obj, vma->va.addr,
+							  dump, vma->gem.offset, vma->va.range);
+			}
 
 		drm_exec_fini(&exec);
 	} else {