From e29bbd5bf0565eaf7c02f85a57b87f66531fa6b3 Mon Sep 17 00:00:00 2001 From: Mike DePaulo Date: Sun, 8 Feb 2015 22:08:09 -0500 Subject: CVE-2014-0210: unvalidated length fields in fs_read_query_info() from xorg/lib/libXfont commit 491291cabf78efdeec8f18b09e14726a9030cc8f fs_read_query_info() parses a reply from the font server. The reply contains embedded length fields, none of which are validated. This can cause out of bound reads in either fs_read_query_info() or in _fs_convert_props() which it calls to parse the fsPropInfo in the reply. v2: apply correctly on nx-libs 3.6.x (Mihai Moldovan) --- nx-X11/lib/font/fc/fserve.c | 43 ++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 40 insertions(+), 3 deletions(-) (limited to 'nx-X11/lib/font/fc/fserve.c') diff --git a/nx-X11/lib/font/fc/fserve.c b/nx-X11/lib/font/fc/fserve.c index 9e652d206..75cabdd9e 100644 --- a/nx-X11/lib/font/fc/fserve.c +++ b/nx-X11/lib/font/fc/fserve.c @@ -866,6 +866,7 @@ fs_read_query_info(FontPathElementPtr fpe, FSBlockDataPtr blockrec) FSFpePtr conn = (FSFpePtr) fpe->private; fsQueryXInfoReply *rep; char *buf; + long bufleft = 0; /* length of reply left to use */ fsPropInfo *pi; fsPropOffset *po; pointer pd; @@ -896,7 +897,10 @@ fs_read_query_info(FontPathElementPtr fpe, FSBlockDataPtr blockrec) buf = (char *) rep; buf += SIZEOF(fsQueryXInfoReply); - + + bufleft = rep->length << 2; + bufleft -= SIZEOF(fsQueryXInfoReply); + /* move the data over */ fsUnpack_XFontInfoHeader(rep, pInfo); @@ -904,19 +908,52 @@ fs_read_query_info(FontPathElementPtr fpe, FSBlockDataPtr blockrec) _fs_init_fontinfo(conn, pInfo); /* Compute offsets into the reply */ + if (bufleft < SIZEOF(fsPropInfo)) + { + ret = -1; +#ifdef DEBUG + fprintf(stderr, "fsQueryXInfo: bufleft (%ld) < SIZEOF(fsPropInfo)\n", + bufleft); +#endif + goto bail; + } pi = (fsPropInfo *) buf; buf += SIZEOF (fsPropInfo); - + bufleft -= SIZEOF (fsPropInfo); + + if ((bufleft / SIZEOF (fsPropOffset)) < pi->num_offsets) + { + ret = -1; +#ifdef DEBUG + fprintf(stderr, + "fsQueryXInfo: (bufleft / SIZEOF (fsPropOffset)) (%ld) < pi->num_offsets (%d)\n", + bufleft / SIZEOF (fsPropOffset), pi->num_offsets); +#endif + goto bail; + } po = (fsPropOffset *) buf; buf += pi->num_offsets * SIZEOF(fsPropOffset); + bufleft -= pi->num_offsets * SIZEOF(fsPropOffset); + if (bufleft < pi->data_len) + { + ret = -1; +#ifdef DEBUG + fprintf(stderr, + "fsQueryXInfo: bufleft (%ld) < data_len (%d)\n", + bufleft, pi->data_len); +#endif + goto bail; + } pd = (pointer) buf; buf += pi->data_len; + bufleft -= pi->data_len; /* convert the properties and step over the reply */ ret = _fs_convert_props(pi, po, pd, pInfo); + bail: _fs_done_read (conn, rep->length << 2); - + if (ret == -1) { fs_cleanup_bfont (bfont); -- cgit v1.2.3