[Mesa-dev] [PATCH] i965: Check return value of screen->image.loader->getBuffers

[Tomasz Figa]

The images struct is an unitialized local variable on the stack. If the
callback returns 0, the struct might not have been updated and so should
be considered unitialized. Currently the code ignores the return value,
which (depending on stack contents) might end up in reading a non-zero
value from images.image_mask and dereferencing further fields.

Another solution would be to initialize image_mask with 0, but checking
the return value seems more sensible and it is what Gallium is doing.

Signed-off-by: Tomasz Figa <tfiga at chromium.org>
---
 src/mesa/drivers/dri/i965/brw_context.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 2504dce..eda54ad 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -1608,6 +1608,7 @@ intel_update_image_buffers(struct brw_context *brw, __DRIdrawable *drawable)
    struct __DRIimageList images;
    unsigned int format;
    uint32_t buffer_mask = 0;
+   int ret;
 
    front_rb = intel_get_renderbuffer(fb, BUFFER_FRONT_LEFT);
    back_rb = intel_get_renderbuffer(fb, BUFFER_BACK_LEFT);
@@ -1627,12 +1628,14 @@ intel_update_image_buffers(struct brw_context *brw, __DRIdrawable *drawable)
    if (back_rb)
       buffer_mask |= __DRI_IMAGE_BUFFER_BACK;
 
-   (*screen->image.loader->getBuffers) (drawable,
+   ret = (*screen->image.loader->getBuffers) (drawable,
                                         driGLFormatToImageFormat(format),
                                         &drawable->dri2.stamp,
                                         drawable->loaderPrivate,
                                         buffer_mask,
                                         &images);
+   if (!ret)
+      return;
 
    if (images.image_mask & __DRI_IMAGE_BUFFER_FRONT) {
       drawable->w = images.front->width;
-- 
2.8.0.rc3.226.g39d4020