From de2d3cb6b870f3d9b8e3e5779415aad079b20633 Mon Sep 17 00:00:00 2001 From: Alan Coopersmith Date: Fri, 1 Mar 2013 21:05:27 -0800 Subject: integer overflow in _XQueryFont() on 32-bit platforms [CVE-2013-1981 1/13] If the CARD32 reply.nCharInfos * sizeof(XCharStruct) overflows an unsigned long, then too small of a buffer will be allocated for the data copied in from the reply. v2: Fix reply_left calculations, check calculated sizes fit in reply_left Reported-by: Ilja Van Sprundel Signed-off-by: Alan Coopersmith Signed-off-by: Julien Cristau Backported-to-NX-by: Ulrich Sibiller --- nx-X11/lib/X11/Font.c | 37 +++++++++++++++++++++++++------------ 1 file changed, 25 insertions(+), 12 deletions(-) (limited to 'nx-X11') diff --git a/nx-X11/lib/X11/Font.c b/nx-X11/lib/X11/Font.c index f60a8a874..820b38944 100644 --- a/nx-X11/lib/X11/Font.c +++ b/nx-X11/lib/X11/Font.c @@ -31,6 +31,7 @@ authorization from the X Consortium and the XFree86 Project. #include #endif #include "Xlibint.h" +#include #if defined(XF86BIGFONT) #define USE_XF86BIGFONT @@ -183,7 +184,8 @@ _XQueryFont ( unsigned long seq) { register XFontStruct *fs; - register long nbytes; + unsigned long nbytes; + unsigned long reply_left; /* unused data words left in reply buffer */ xQueryFontReply reply; register xResourceReq *req; register _XExtension *ext; @@ -211,9 +213,10 @@ _XQueryFont ( } if (seq) DeqAsyncHandler(dpy, &async); + reply_left = reply.length - + ((SIZEOF(xQueryFontReply) - SIZEOF(xReply)) >> 2); if (! (fs = (XFontStruct *) Xmalloc (sizeof (XFontStruct)))) { - _XEatData(dpy, (unsigned long)(reply.nFontProps * SIZEOF(xFontProp) + - reply.nCharInfos * SIZEOF(xCharInfo))); + _XEatDataWords(dpy, reply_left); return (XFontStruct *)NULL; } fs->ext_data = NULL; @@ -239,32 +242,42 @@ _XQueryFont ( */ fs->properties = NULL; if (fs->n_properties > 0) { - nbytes = reply.nFontProps * sizeof(XFontProp); - fs->properties = (XFontProp *) Xmalloc ((unsigned) nbytes); + /* nFontProps is a CARD16 */ nbytes = reply.nFontProps * SIZEOF(xFontProp); + if ((nbytes >> 2) <= reply_left) { + size_t pbytes = reply.nFontProps * sizeof(XFontProp); + fs->properties = Xmalloc (pbytes); + } if (! fs->properties) { Xfree((char *) fs); - _XEatData(dpy, (unsigned long) - (nbytes + reply.nCharInfos * SIZEOF(xCharInfo))); + _XEatDataWords(dpy, reply_left); return (XFontStruct *)NULL; } _XRead32 (dpy, (long *)fs->properties, nbytes); + reply_left -= (nbytes >> 2); } /* * If no characters in font, then it is a bad font, but * shouldn't try to read nothing. */ + /* have to unpack charinfos on some machines (CRAY) */ fs->per_char = NULL; if (reply.nCharInfos > 0){ - nbytes = reply.nCharInfos * sizeof(XCharStruct); - if (! (fs->per_char = (XCharStruct *) Xmalloc ((unsigned) nbytes))) { + /* nCharInfos is a CARD32 */ + if (reply.nCharInfos < (INT_MAX / sizeof(XCharStruct))) { + nbytes = reply.nCharInfos * SIZEOF(xCharInfo); + if ((nbytes >> 2) <= reply_left) { + size_t cibytes = reply.nCharInfos * sizeof(XCharStruct); + fs->per_char = Xmalloc (cibytes); + } + } + if (! fs->per_char) { if (fs->properties) Xfree((char *) fs->properties); Xfree((char *) fs); - _XEatData(dpy, (unsigned long) - (reply.nCharInfos * SIZEOF(xCharInfo))); + _XEatDataWords(dpy, reply_left); return (XFontStruct *)NULL; } - nbytes = reply.nCharInfos * SIZEOF(xCharInfo); + _XRead16 (dpy, (char *)fs->per_char, nbytes); } -- cgit v1.2.3