[Mesa-dev] [PATCH] i965: miptree: prevent potential NULL pointer access

[Lionel Landwerlin]

If the mcs buffer allocation fails we might get a NULL pointer. This
was reported by Coverity and should only happen if we run out of
memory.

CID: 1394290
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
---
 src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index 6c81ffb..2115e09 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -1486,6 +1486,8 @@ intel_miptree_init_mcs(struct brw_context *brw,
                        struct intel_mipmap_tree *mt,
                        int init_value)
 {
+   assert(mt->mcs_buf != NULL);
+
    /* From the Ivy Bridge PRM, Vol 2 Part 1 p326:
     *
     *     When MCS buffer is enabled and bound to MSRT, it is required that it
@@ -1605,7 +1607,8 @@ intel_miptree_alloc_mcs(struct brw_context *brw,
                                    mt->logical_height0,
                                    MIPTREE_LAYOUT_ACCELERATED_UPLOAD);
 
-   intel_miptree_init_mcs(brw, mt, 0xFF);
+   if (mt->mcs_buf)
+      intel_miptree_init_mcs(brw, mt, 0xFF);
 
    return mt->mcs_buf != NULL;
 }
@@ -1671,7 +1674,7 @@ intel_miptree_alloc_non_msrt_mcs(struct brw_context *brw,
     * used for lossless compression which requires similar initialisation
     * as multi-sample compression.
     */
-   if (is_lossless_compressed) {
+   if (mt->mcs_buf && is_lossless_compressed) {
       /* Hardware sets the auxiliary buffer to all zeroes when it does full
        * resolve. Initialize it accordingly in case the first renderer is
        * cpu (or other none compression aware party).
-- 
2.10.2