[Mesa-dev] [PATCH 2/2] egl: Restrict multiplication in calloc arguments to use compile-time constants

[Carl Worth]

As explained in the previous commit, we want to avoid the possibility of
integer-multiplication overflow while allocating buffers.

In these two cases, the final allocation size is the product of three values:
one variable and two that are fixed constants at compile time.

In this commit, we move the explicit multiplication to involve only the
compile-time constants, preventing any overflow from that multiplication, (and
allowing calloc to catch any potential overflow from the remainining implicit
multiplication).
---
 src/egl/drivers/dri2/platform_drm.c     | 2 +-
 src/egl/drivers/dri2/platform_wayland.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/egl/drivers/dri2/platform_drm.c b/src/egl/drivers/dri2/platform_drm.c
index e272beb..70bd7d4 100644
--- a/src/egl/drivers/dri2/platform_drm.c
+++ b/src/egl/drivers/dri2/platform_drm.c
@@ -352,7 +352,7 @@ dri2_drm_get_buffers(__DRIdrawable * driDrawable,
    const unsigned int format = 32;
    int i;
 
-   attachments_with_format = calloc(count * 2, sizeof(unsigned int));
+   attachments_with_format = calloc(count, 2 * sizeof(unsigned int));
    if (!attachments_with_format) {
       *out_count = 0;
       return NULL;
diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c
index 537d26e..59b2792 100644
--- a/src/egl/drivers/dri2/platform_wayland.c
+++ b/src/egl/drivers/dri2/platform_wayland.c
@@ -468,7 +468,7 @@ dri2_wl_get_buffers(__DRIdrawable * driDrawable,
    const unsigned int format = 32;
    int i;
 
-   attachments_with_format = calloc(count * 2, sizeof(unsigned int));
+   attachments_with_format = calloc(count, 2 * sizeof(unsigned int));
    if (!attachments_with_format) {
       *out_count = 0;
       return NULL;
-- 
2.1.0