[PATCH 3.16 082/294] drm/msm: Fix potential buffer overflow issue

[Ben Hutchings]

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Kasin Li <donglil@xxxxxxxxxxxxxx>

commit 4a630fadbb29d9efaedb525f1a8f7449ad107641 upstream.

In function submit_create, if nr_cmds or nr_bos is assigned with
negative value, the allocated buffer may be small than intended.
Using this buffer will lead to buffer overflow issue.

Signed-off-by: Kasin Li <donglil@xxxxxxxxxxxxxx>
Signed-off-by: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
Signed-off-by: Rob Clark <robdclark@xxxxxxxxx>
[bwh: Backported to 3.16: submit_create() only supports a variable number of bos]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -34,10 +34,13 @@ static inline void __user *to_user_ptr(u
 }
 
 static struct msm_gem_submit *submit_create(struct drm_device *dev,
-		struct msm_gpu *gpu, int nr)
+		struct msm_gpu *gpu, uint32_t nr)
 {
 	struct msm_gem_submit *submit;
-	int sz = sizeof(*submit) + (nr * sizeof(submit->bos[0]));
+	uint64_t sz = sizeof(*submit) + (nr * sizeof(submit->bos[0]));
+
+	if (sz > SIZE_MAX)
+		return NULL;
 
 	submit = kmalloc(sz, GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY);
 	if (submit) {