This is a note to let you know that I've just added the patch titled

    drm/i915: bounds check execbuffer relocation count

to the 3.0-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-i915-bounds-check-execbuffer-relocation-count.patch
and it can be found in the queue-3.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


>From 3118a4f652c7b12c752f3222af0447008f9b2368 Mon Sep 17 00:00:00 2001
From: Kees Cook <[email protected]>
Date: Mon, 11 Mar 2013 17:31:45 -0700
Subject: drm/i915: bounds check execbuffer relocation count

From: Kees Cook <[email protected]>

commit 3118a4f652c7b12c752f3222af0447008f9b2368 upstream.

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 <[email protected]>
Reported-by: Pinkie Pie
Reviewed-by: Chris Wilson <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -888,15 +888,20 @@ validate_exec_list(struct drm_i915_gem_e
                   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;
                int length; /* limited by fault_in_pages_readable() */
 
-               /* 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);


Patches currently in stable-queue which might be from [email protected] are

queue-3.0/drm-i915-bounds-check-execbuffer-relocation-count.patch
queue-3.0/drm-i915-restrict-kernel-address-leak-in-debugfs.patch
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