On 05/23/2013 08:44 AM, Alan Coopersmith wrote:
busIdStringLength is a CARD32 and needs to be bounds checked before adding
one to it to come up with the total size to allocate, to avoid integer
overflow leading to underallocation and writing data from the network past
the end of the allocated buffer.
Reported-by: Ilja Van Sprundel <ivansprun...@ioactive.com>
Signed-off-by: Alan Coopersmith <alan.coopersm...@oracle.com>
---
src/glx/XF86dri.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/src/glx/XF86dri.c b/src/glx/XF86dri.c
index b1cdc9b..8f53bd7 100644
--- a/src/glx/XF86dri.c
+++ b/src/glx/XF86dri.c
@@ -43,6 +43,7 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#include <X11/extensions/Xext.h>
#include <X11/extensions/extutil.h>
#include "xf86dristr.h"
+#include <limits.h>
static XExtensionInfo _xf86dri_info_data;
static XExtensionInfo *xf86dri_info = &_xf86dri_info_data;
@@ -201,7 +202,11 @@ XF86DRIOpenConnection(Display * dpy, int screen,
drm_handle_t * hSAREA,
}
if (rep.length) {
- if (!(*busIdString = calloc(rep.busIdStringLength + 1, 1))) {
+ if (rep.busIdStringLength < INT_MAX)
+ *busIdString = calloc(rep.busIdStringLength + 1, 1);
But calloc takes size_t, and size_t is unsigned. That makes this look a
little weird. The problem is when rep.busIdStringLength is INT_MAX, the
problem occurs when it's UINT_MAX. Right?
Even this is only a problem because of calloc's zero size handling behavior:
If nmemb or size is 0, then calloc() returns either NULL, or
a unique pointer value that can later be successfully passed
to free().
Good times.
+ else
+ *busIdString = NULL;
+ if (*busIdString == NULL) {
_XEatData(dpy, ((rep.busIdStringLength + 3) & ~3));
Doesn't this have a similar overflow issue? If rep.busIdStringLength is
UINT_MAX-2, the result is 0.
UnlockDisplay(dpy);
SyncHandle();
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