commit: 3118a4f652c7b12c752f3222af0447008f9b2368
From: Kees Cook <keescook@xxxxxxxxxxxx>
Date: Mon, 11 Mar 2013 17:31:45 -0700
Subject: drm/i915: bounds check execbuffer relocation count
It is possible to wrap the counter used to allocate the buffer for
relocation copies. This could lead to heap writing overflows.
CVE-2013-0913
v3: collapse test, improve comment
v2: move check into validate_exec_list
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reported-by: Pinkie Pie
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 2f2daeb..3b11ab0 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -732,6 +732,8 @@ validate_exec_list(struct drm_i915_gem_exec_object2 *exec,
int count)
{
int i;
+ int relocs_total = 0;
+ int relocs_max = INT_MAX / sizeof(struct drm_i915_gem_relocation_entry);
for (i = 0; i < count; i++) {
char __user *ptr = (char __user *)(uintptr_t)exec[i].relocs_ptr;
@@ -740,10 +742,13 @@ validate_exec_list(struct drm_i915_gem_exec_object2 *exec,
if (exec[i].flags & __EXEC_OBJECT_UNKNOWN_FLAGS)
return -EINVAL;
- /* First check for malicious input causing overflow */
- if (exec[i].relocation_count >
- INT_MAX / sizeof(struct drm_i915_gem_relocation_entry))
+ /* First check for malicious input causing overflow in
+ * the worst case where we need to allocate the entire
+ * relocation tree as a single array.
+ */
+ if (exec[i].relocation_count > relocs_max - relocs_total)
return -EINVAL;
+ relocs_total += exec[i].relocation_count;
length = exec[i].relocation_count *
sizeof(struct drm_i915_gem_relocation_entry);
--
1.7.10.4
--
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