main/libxinerama: fix CVE-2013-1985

ref #1931

1 files changed, 76 insertions, 0 deletions

diff --git a/main/libxinerama/0002-integer-overflow-in-XineramaQueryScreens-CVE-2013-19.patch b/main/libxinerama/0002-integer-overflow-in-XineramaQueryScreens-CVE-2013-19.patch
new file mode 100644
index 000000000..a0ce966b9
--- /dev/null
+++ b/main/libxinerama/0002-integer-overflow-in-XineramaQueryScreens-CVE-2013-19.patch
@@ -0,0 +1,76 @@
+From 99c644fc8488657bdd106717df7446d606f9ef22 Mon Sep 17 00:00:00 2001
+From: Alan Coopersmith <alan.coopersmith@oracle.com>
+Date: Fri, 8 Mar 2013 19:55:55 -0800
+Subject: [PATCH 2/2] integer overflow in XineramaQueryScreens()
+ [CVE-2013-1985]
+
+If the reported number of screens is too large, the calculations to
+allocate memory for them may overflow, leaving us writing beyond the
+bounds of the allocation.
+
+Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
+Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
+---
+ src/Xinerama.c | 44 ++++++++++++++++++++++++++++----------------
+ 1 file changed, 28 insertions(+), 16 deletions(-)
+
+diff --git a/src/Xinerama.c b/src/Xinerama.c
+index 04189b6..67a35b5 100644
+--- a/src/Xinerama.c
++++ b/src/Xinerama.c
+@@ -303,24 +303,36 @@ XineramaQueryScreens(
+ 	return NULL;
+     }
+ 
+-    if(rep.number) {
+-	if((scrnInfo = Xmalloc(sizeof(XineramaScreenInfo) * rep.number))) {
++    /*
++     * rep.number is a CARD32 so could be as large as 2^32
++     * The X11 protocol limits the total screen size to 64k x 64k,
++     * and no screen can be smaller than a pixel.  While technically
++     * that means we could theoretically reach 2^32 screens, and that's
++     * not even taking overlap into account, Xorg is currently limited
++     * to 16 screens, and few known servers have a much higher limit,
++     * so 1024 seems more than enough to prevent both integer overflow
++     * and insane X server responses causing massive memory allocation.
++     */
++    if ((rep.number > 0) && (rep.number <= 1024))
++	scrnInfo = Xmalloc(sizeof(XineramaScreenInfo) * rep.number);
++    if (scrnInfo != NULL) {
++	int i;
++
++	for (i = 0; i < rep.number; i++) {
+ 	    xXineramaScreenInfo scratch;
+-	    int i;
+-
+-	    for(i = 0; i < rep.number; i++) {
+-		_XRead(dpy, (char*)(&scratch), sz_XineramaScreenInfo);
+-		scrnInfo[i].screen_number = i;
+-		scrnInfo[i].x_org 	  = scratch.x_org;
+-		scrnInfo[i].y_org 	  = scratch.y_org;
+-		scrnInfo[i].width 	  = scratch.width;
+-		scrnInfo[i].height 	  = scratch.height;
+-	    }
+-
+-	    *number = rep.number;
+-	} else
+-	    _XEatDataWords(dpy, rep.length);
++
++	    _XRead(dpy, (char*)(&scratch), sz_XineramaScreenInfo);
++
++	    scrnInfo[i].screen_number = i;
++	    scrnInfo[i].x_org	= scratch.x_org;
++	    scrnInfo[i].y_org	= scratch.y_org;
++	    scrnInfo[i].width	= scratch.width;
++	    scrnInfo[i].height	= scratch.height;
++	}
++
++	*number = rep.number;
+     } else {
++	_XEatDataWords(dpy, rep.length);
+ 	*number = 0;
+     }
+ 
+-- 
+1.8.2.3
+