integer overflow in XF86DRIGetClientDriverName() [CVE-2013-1993 2/2]

clientDriverNameLength 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.

NOTE: This is a candidate for stable release branches.

Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

diff --git a/src/glx/XF86dri.c b/src/glx/XF86dri.c
index 8f53bd71953c028a2499cf8f671f12ee9e598f4a..56e355706017e433cb42540ef3020be8b415b00a 100644 (file)
--- a/src/glx/XF86dri.c
+++ b/src/glx/XF86dri.c
@@ -305,9 +305,11 @@ XF86DRIGetClientDriverName(Display * dpy, int screen,
    *ddxDriverPatchVersion = rep.ddxDriverPatchVersion;
 
    if (rep.length) {
-      if (!
-          (*clientDriverName =
-           calloc(rep.clientDriverNameLength + 1, 1))) {
+      if (rep.clientDriverNameLength < INT_MAX)
+         *clientDriverName = calloc(rep.clientDriverNameLength + 1, 1);
+      else
+         *clientDriverName = NULL;
+      if (*clientDriverName == NULL) {
          _XEatData(dpy, ((rep.clientDriverNameLength + 3) & ~3));
          UnlockDisplay(dpy);
          SyncHandle();