CVE-2013-0913 drm/i915: head writing overflow (rhbz 920471 920529)

1 files changed, 100 insertions, 0 deletions

diff --git a/drm-i915-bounds-check-execbuffer-relocation-count.patch b/drm-i915-bounds-check-execbuffer-relocation-count.patch
new file mode 100644
index 000000000..1377a5285
--- /dev/null
+++ b/drm-i915-bounds-check-execbuffer-relocation-count.patch
@@ -0,0 +1,100 @@
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+Date:	Mon, 11 Mar 2013 17:31:45 -0700
+From:	Kees Cook <keescook@chromium.org>
+To:	linux-kernel@vger.kernel.org
+Cc:	Daniel Vetter <daniel.vetter@ffwll.ch>,
+	David Airlie <airlied@linux.ie>,
+	dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
+	Julien Tinnes <jln@google.com>, marcheu@chromium.org
+Subject: [PATCH v3] drm/i915: bounds check execbuffer relocation count
+Message-ID: <20130312003145.GA28993@www.outflux.net>
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+
+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@chromium.org>
+Reported-by: Pinkie Pie
+Cc: stable@vger.kernel.org
+---
+ 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 b3a40ee..094ba41 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);
+-- 
+1.7.9.5
+
+
+-- 
+Kees Cook
+Chrome OS Security
+--
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