1 files changed, 74 insertions, 0 deletions
diff --git a/x11/modular-xorg-server/patches/patch-dix_dixfonts.c b/x11/modular-xorg-server/patches/patch-dix_dixfonts.c
new file mode 100644
index 00000000000..f7eaf532e2e
--- /dev/null
+++ b/x11/modular-xorg-server/patches/patch-dix_dixfonts.c
@@ -0,0 +1,74 @@
+$NetBSD: patch-dix_dixfonts.c,v 1.1.2.2 2013/10/09 07:36:30 spz Exp $
+
+Fix CVE-2013-4396.
+
+From a4d9bf1259ad28f54b6d59a480b2009cc89ca623 Mon Sep 17 00:00:00 2001
+From: Alan Coopersmith <alan.coopersmith@oracle.com>
+Date: Mon, 16 Sep 2013 21:47:16 -0700
+Subject: [PATCH] Avoid use-after-free in dix/dixfonts.c: doImageText()
+
+Save a pointer to the passed in closure structure before copying it
+and overwriting the *c pointer to point to our copy instead of the
+original.  If we hit an error, once we free(c), reset c to point to
+the original structure before jumping to the cleanup code that
+references *c.
+
+Since one of the errors being checked for is whether the server was
+able to malloc(c->nChars * itemSize), the client can potentially pass
+a number of characters chosen to cause the malloc to fail and the
+error path to be taken, resulting in the read from freed memory.
+
+Since the memory is accessed almost immediately afterwards, and the
+X server is mostly single threaded, the odds of the free memory having
+invalid contents are low with most malloc implementations when not using
+memory debugging features, but some allocators will definitely overwrite
+the memory there, leading to a likely crash.
+
+Reported-by: Pedro Ribeiro <pedrib@gmail.com>
+Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
+Reviewed-by: Julien Cristau <jcristau@debian.org>
+---
+ dix/dixfonts.c |    5 +++++
+ 1 file changed, 5 insertions(+)
+
+--- dix/dixfonts.c.orig	2012-05-17 17:09:01.000000000 +0000
++++ dix/dixfonts.c
+@@ -1414,6 +1414,7 @@ doImageText(ClientPtr client, ITclosureP
+             GC *pGC;
+             unsigned char *data;
+             ITclosurePtr new_closure;
++            ITclosurePtr old_closure;
+ 
+             /* We're putting the client to sleep.  We need to
+                save some state.  Similar problem to that handled
+@@ -1425,12 +1426,14 @@ doImageText(ClientPtr client, ITclosureP
+                 err = BadAlloc;
+                 goto bail;
+             }
++            old_closure = c;
+             *new_closure = *c;
+             c = new_closure;
+ 
+             data = malloc(c->nChars * itemSize);
+             if (!data) {
+                 free(c);
++                c = old_closure;
+                 err = BadAlloc;
+                 goto bail;
+             }
+@@ -1441,6 +1444,7 @@ doImageText(ClientPtr client, ITclosureP
+             if (!pGC) {
+                 free(c->data);
+                 free(c);
++                c = old_closure;
+                 err = BadAlloc;
+                 goto bail;
+             }
+@@ -1453,6 +1457,7 @@ doImageText(ClientPtr client, ITclosureP
+                 FreeScratchGC(pGC);
+                 free(c->data);
+                 free(c);
++                c = old_closure;
+                 err = BadAlloc;
+                 goto bail;
+             }