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From ef439da38d3a4c00a4e03e7d8f83cb359cd9a230 Mon Sep 17 00:00:00 2001
From: Mike DePaulo <mikedep333@gmail.com>
Date: Sun, 8 Feb 2015 22:35:21 -0500
Subject: [PATCH 16/40] CVE-2014-0210: unvalidated length fields in
fs_read_list() from xorg/lib/libXfont commit
5fa73ac18474be3032ee7af9c6e29deab163ea39
fs_read_list() parses a reply from the font server. The reply
contains a list of strings with embedded length fields, none of
which are validated. This can cause out of bound reads when looping
over the strings in the reply.
---
nx-X11/lib/font/fc/fserve.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
--- a/nx-X11/lib/font/fc/fserve.c
+++ b/nx-X11/lib/font/fc/fserve.c
@@ -2366,6 +2366,7 @@ fs_read_list(FontPathElementPtr fpe, FSB
FSBlockedListPtr blist = (FSBlockedListPtr) blockrec->data;
fsListFontsReply *rep;
char *data;
+ long dataleft; /* length of reply left to use */
int length,
i,
ret;
@@ -2383,16 +2384,30 @@ fs_read_list(FontPathElementPtr fpe, FSB
return AllocError;
}
data = (char *) rep + SIZEOF (fsListFontsReply);
+ dataleft = (rep->length << 2) - SIZEOF (fsListFontsReply);
err = Successful;
/* copy data into FontPathRecord */
for (i = 0; i < rep->nFonts; i++)
{
+ if (dataleft < 1)
+ break;
length = *(unsigned char *)data++;
+ dataleft--; /* used length byte */
+ if (length > dataleft) {
+#ifdef DEBUG
+ fprintf(stderr,
+ "fsListFonts: name length (%d) > dataleft (%ld)\n",
+ length, dataleft);
+#endif
+ err = BadFontName;
+ break;
+ }
err = AddFontNamesName(blist->names, data, length);
if (err != Successful)
break;
data += length;
+ dataleft -= length;
}
_fs_done_read (conn, rep->length << 2);
return err;
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