From d05f27a6f74cb419ad5a437f2e4690b17e7faee5 Mon Sep 17 00:00:00 2001 From: Alan Coopersmith Date: Sat, 9 Mar 2013 14:40:33 -0800 Subject: [PATCH 2/7] integer overflow in XcupGetReservedColormapEntries() [CVE-2013-1982 1/6] If the computed number of entries is large enough that it overflows when multiplied by the size of a xColorItem struct, or is treated as negative when compared to the size of the stack allocated buffer, then memory corruption can occur when more bytes are read from the X server than the size of the buffer we allocated to hold them. Reported-by: Ilja Van Sprundel Signed-off-by: Alan Coopersmith --- src/Xcup.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/src/Xcup.c b/src/Xcup.c index 1f1d625..670f356 100644 --- a/src/Xcup.c +++ b/src/Xcup.c @@ -36,6 +36,7 @@ in this Software without prior written authorization from The Open Group. #include #include #include +#include #include "eat.h" static XExtensionInfo _xcup_info_data; @@ -134,15 +135,19 @@ XcupGetReservedColormapEntries( req->xcupReqType = X_XcupGetReservedColormapEntries; req->screen = screen; if (_XReply(dpy, (xReply *)&rep, 0, xFalse)) { - long nbytes; + unsigned long nbytes; xColorItem* rbufp; - int nentries = rep.length / 3; + unsigned int nentries = rep.length / 3; - nbytes = nentries * SIZEOF (xColorItem); - if (nentries > TYP_RESERVED_ENTRIES) - rbufp = (xColorItem*) Xmalloc (nbytes); - else - rbufp = rbuf; + if (nentries < (INT_MAX / SIZEOF (xColorItem))) { + nbytes = nentries * SIZEOF (xColorItem); + + if (nentries > TYP_RESERVED_ENTRIES) + rbufp = Xmalloc (nbytes); + else + rbufp = rbuf; + } else + rbufp = NULL; if (rbufp == NULL) { _XEatDataWords(dpy, rep.length); -- 1.8.2.3