[PATCH 5/5] Xephyr: integer overflow in XF86DRIGetClientDriverName()

[Alan Coopersmith]

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.

Reported-by: Ilja Van Sprundel <ivansprundel at ioactive.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
---
 hw/kdrive/ephyr/XF86dri.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/kdrive/ephyr/XF86dri.c b/hw/kdrive/ephyr/XF86dri.c
index b1f070e..6a4c6c5 100644
--- a/hw/kdrive/ephyr/XF86dri.c
+++ b/hw/kdrive/ephyr/XF86dri.c
@@ -327,9 +327,11 @@ XF86DRIGetClientDriverName(Display * dpy, int screen,
     *ddxDriverPatchVersion = rep.ddxDriverPatchVersion;
 
     if (rep.length) {
-        if (!
-            (*clientDriverName =
-             (char *) 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();
-- 
1.7.9.2