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authorAlan Coopersmith <alan.coopersmith@oracle.com>2013-03-02 15:08:21 -0800
committerUlrich Sibiller <uli42@gmx.de>2016-10-12 09:34:39 +0200
commitdbc11719399ce7e191c806ad6b5c9104666e2a77 (patch)
treeae13d49a7610df7371b0181486dc7ccaf2b759ee /nx-X11/lib/X11
parent77edd88e104cbd3fb5dc95473adac1db2c2302a3 (diff)
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Avoid overflows in XListExtensions() [CVE-2013-1997 15/15]
Ensure that when breaking the returned list into individual strings, we don't walk past the end of allocated memory to write the '\0' bytes Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com> Reviewed-by: Matthieu Herrb <matthieu.herrb@laas.fr> Signed-off-by: Julien Cristau <jcristau@debian.org> Backported-to-NX-by: Ulrich Sibiller <uli42@gmx.de>
Diffstat (limited to 'nx-X11/lib/X11')
-rw-r--r--nx-X11/lib/X11/ListExt.c36
1 files changed, 22 insertions, 14 deletions
diff --git a/nx-X11/lib/X11/ListExt.c b/nx-X11/lib/X11/ListExt.c
index 16b522e88..e925c4773 100644
--- a/nx-X11/lib/X11/ListExt.c
+++ b/nx-X11/lib/X11/ListExt.c
@@ -28,18 +28,21 @@ in this Software without prior written authorization from The Open Group.
#include <config.h>
#endif
#include "Xlibint.h"
+#include <limits.h>
char **XListExtensions(
register Display *dpy,
int *nextensions) /* RETURN */
{
xListExtensionsReply rep;
- char **list;
- char *ch;
+ char **list = NULL;
+ char *ch = NULL;
+ char *chend;
+ int count = 0;
register unsigned i;
register int length;
register xReq *req;
- register long rlen;
+ unsigned long rlen;
LockDisplay(dpy);
GetEmptyReq (ListExtensions, req);
@@ -51,16 +54,17 @@ char **XListExtensions(
}
if (rep.nExtensions) {
- list = (char **) Xmalloc (
- (unsigned)(rep.nExtensions * sizeof (char *)));
- rlen = rep.length << 2;
- ch = (char *) Xmalloc ((unsigned) rlen + 1);
+ list = Xmalloc (rep.nExtensions * sizeof (char *));
+ if (rep.length < (LONG_MAX >> 2)) {
+ rlen = rep.length << 2;
+ ch = Xmalloc (rlen + 1);
/* +1 to leave room for last null-terminator */
+ }
if ((!list) || (!ch)) {
if (list) Xfree((char *) list);
if (ch) Xfree((char *) ch);
- _XEatData(dpy, (unsigned long) rlen);
+ _XEatDataWords(dpy, rep.length);
UnlockDisplay(dpy);
SyncHandle();
return (char **) NULL;
@@ -70,17 +74,21 @@ char **XListExtensions(
/*
* unpack into null terminated strings.
*/
+ chend = ch + (rlen + 1);
length = *ch;
for (i = 0; i < rep.nExtensions; i++) {
- list[i] = ch+1; /* skip over length */
- ch += length + 1; /* find next length ... */
- length = *ch;
- *ch = '\0'; /* and replace with null-termination */
+ if (ch + length < chend) {
+ list[i] = ch+1; /* skip over length */
+ ch += length + 1; /* find next length ... */
+ length = *ch;
+ *ch = '\0'; /* and replace with null-termination */
+ count++;
+ } else
+ list[i] = NULL;
}
}
- else list = (char **) NULL;
- *nextensions = rep.nExtensions;
+ *nextensions = count;
UnlockDisplay(dpy);
SyncHandle();
return (list);