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| author | Alan Coopersmith <alan.coopersmith@oracle.com> | 2013-03-01 21:05:27 -0800 |
|---|---|---|
| committer | Ulrich Sibiller <uli42@gmx.de> | 2016-10-12 09:34:38 +0200 |
| commit | dda0c652f1ec6d935040daaf2755bf9f2f6d3c4b (patch) | |
| tree | 80d23e2e75ec2069b17d56c4e767e46cb22943be | |
| parent | de2d3cb6b870f3d9b8e3e5779415aad079b20633 (diff) | |
| download | nx-libs-dda0c652f1ec6d935040daaf2755bf9f2f6d3c4b.tar.gz nx-libs-dda0c652f1ec6d935040daaf2755bf9f2f6d3c4b.tar.bz2 nx-libs-dda0c652f1ec6d935040daaf2755bf9f2f6d3c4b.zip | |
integer overflow in _XF86BigfontQueryFont() [CVE-2013-1981 2/13]
Similar to _XQueryFont, but with more ways to go wrong and overflow.
Only compiled if libX11 is built with XF86BigFont support.
v2: Fix reply_left calculations, check calculated sizes fit in reply_left
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Signed-off-by: Julien Cristau <jcristau@debian.org>
Backported-to-NX-by: Ulrich Sibiller <uli42@gmx.de>
| -rw-r--r-- | nx-X11/lib/X11/Font.c | 42 |
1 files changed, 25 insertions, 17 deletions
diff --git a/nx-X11/lib/X11/Font.c b/nx-X11/lib/X11/Font.c index 820b38944..0501ae279 100644 --- a/nx-X11/lib/X11/Font.c +++ b/nx-X11/lib/X11/Font.c @@ -404,7 +404,8 @@ _XF86BigfontQueryFont ( unsigned long seq) { register XFontStruct *fs; - register long nbytes; + unsigned long nbytes; + unsigned long reply_left; /* unused data left in reply buffer */ xXF86BigfontQueryFontReply reply; register xXF86BigfontQueryFontReq *req; register _XExtension *ext; @@ -457,13 +458,10 @@ _XF86BigfontQueryFont ( DeqAsyncHandler(dpy, &async2); if (seq) DeqAsyncHandler(dpy, &async1); + reply_left = reply.length - + ((SIZEOF(xXF86BigfontQueryFontReply) - SIZEOF(xReply)) >> 2); if (! (fs = (XFontStruct *) Xmalloc (sizeof (XFontStruct)))) { - _XEatData(dpy, - reply.nFontProps * SIZEOF(xFontProp) - + (reply.nCharInfos > 0 && reply.shmid == (CARD32)(-1) - ? reply.nUniqCharInfos * SIZEOF(xCharInfo) - + (reply.nCharInfos+1)/2 * 2 * sizeof(CARD16) - : 0)); + _XEatDataWords(dpy, reply_left); return (XFontStruct *)NULL; } fs->ext_data = NULL; @@ -489,23 +487,32 @@ _XF86BigfontQueryFont ( */ 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, - nbytes - + (reply.nCharInfos > 0 && reply.shmid == (CARD32)(-1) - ? reply.nUniqCharInfos * SIZEOF(xCharInfo) - + (reply.nCharInfos+1)/2 * 2 * sizeof(CARD16) - : 0)); + _XEatDataWords(dpy, reply_left); return (XFontStruct *)NULL; } _XRead32 (dpy, (long *)fs->properties, nbytes); + reply_left -= (nbytes >> 2); } fs->per_char = NULL; +#ifndef LONG64 + /* compares each part to half the maximum, which should be far more than + any real font needs, so the combined total doesn't overflow either */ + if (reply.nUniqCharInfos > ((ULONG_MAX / 2) / SIZEOF(xCharInfo)) || + reply.nCharInfos > ((ULONG_MAX / 2) / sizeof(CARD16))) { + Xfree((char *) fs); + _XEatDataWords(dpy, reply_left); + return (XFontStruct *)NULL; + } +#endif if (reply.nCharInfos > 0) { /* fprintf(stderr, "received font metrics, nCharInfos = %d, nUniqCharInfos = %d, shmid = %d\n", reply.nCharInfos, reply.nUniqCharInfos, reply.shmid); */ if (reply.shmid == (CARD32)(-1)) { @@ -519,14 +526,14 @@ _XF86BigfontQueryFont ( if (!pUniqCI) { if (fs->properties) Xfree((char *) fs->properties); Xfree((char *) fs); - _XEatData(dpy, nbytes); + _XEatDataWords(dpy, reply_left); return (XFontStruct *)NULL; } if (! (fs->per_char = (XCharStruct *) Xmalloc (reply.nCharInfos * sizeof(XCharStruct)))) { Xfree((char *) pUniqCI); if (fs->properties) Xfree((char *) fs->properties); Xfree((char *) fs); - _XEatData(dpy, nbytes); + _XEatDataWords(dpy, reply_left); return (XFontStruct *)NULL; } _XRead16 (dpy, (char *) pUniqCI, nbytes); @@ -581,6 +588,7 @@ _XF86BigfontQueryFont ( if (!(extcodes->serverCapabilities & CAP_VerifiedLocal)) { struct shmid_ds buf; if (!(shmctl(reply.shmid, IPC_STAT, &buf) >= 0 + && reply.nCharInfos < (LONG_MAX / sizeof(XCharStruct)) && buf.shm_segsz >= reply.shmsegoffset + reply.nCharInfos * sizeof(XCharStruct) + sizeof(CARD32) && *(CARD32 *)(addr + reply.shmsegoffset + reply.nCharInfos * sizeof(XCharStruct)) == extcodes->serverSignature)) { shmdt(addr); |