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From 520683652564c2a4e42328ae23eef9bb63271565 Mon Sep 17 00:00:00 2001
From: Alan Coopersmith <alan.coopersmith@oracle.com>
Date: Fri, 25 Apr 2014 23:03:24 -0700
Subject: [PATCH 10/12] CVE-2014-0210: unvalidated length fields in
fs_read_glyphs()
fs_read_glyphs() 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 when looping over the glyph
bitmaps in the reply.
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Matthieu Herrb <matthieu@herrb.eu>
---
src/fc/fserve.c | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)
diff --git a/src/fc/fserve.c b/src/fc/fserve.c
index 232e969..581bb1b 100644
--- a/src/fc/fserve.c
+++ b/src/fc/fserve.c
@@ -1907,6 +1907,7 @@ fs_read_glyphs(FontPathElementPtr fpe, FSBlockDataPtr blockrec)
FontInfoPtr pfi = &pfont->info;
fsQueryXBitmaps16Reply *rep;
char *buf;
+ long bufleft; /* length of reply left to use */
fsOffset32 *ppbits;
fsOffset32 local_off;
char *off_adr;
@@ -1938,9 +1939,33 @@ fs_read_glyphs(FontPathElementPtr fpe, FSBlockDataPtr blockrec)
buf = (char *) rep;
buf += SIZEOF (fsQueryXBitmaps16Reply);
+ bufleft = rep->length << 2;
+ bufleft -= SIZEOF (fsQueryXBitmaps16Reply);
+
+ if ((bufleft / SIZEOF (fsOffset32)) < rep->num_chars)
+ {
+#ifdef DEBUG
+ fprintf(stderr,
+ "fsQueryXBitmaps16: num_chars (%d) > bufleft (%ld) / %d\n",
+ rep->num_chars, bufleft, SIZEOF (fsOffset32));
+#endif
+ err = AllocError;
+ goto bail;
+ }
ppbits = (fsOffset32 *) buf;
buf += SIZEOF (fsOffset32) * (rep->num_chars);
+ bufleft -= SIZEOF (fsOffset32) * (rep->num_chars);
+ if (bufleft < rep->nbytes)
+ {
+#ifdef DEBUG
+ fprintf(stderr,
+ "fsQueryXBitmaps16: nbytes (%d) > bufleft (%ld)\n",
+ rep->nbytes, bufleft);
+#endif
+ err = AllocError;
+ goto bail;
+ }
pbitmaps = (pointer ) buf;
if (blockrec->type == FS_LOAD_GLYPHS)
@@ -1998,7 +2023,9 @@ fs_read_glyphs(FontPathElementPtr fpe, FSBlockDataPtr blockrec)
*/
if (NONZEROMETRICS(&fsdata->encoding[minchar].metrics))
{
- if (local_off.length)
+ if (local_off.length &&
+ (local_off.position < rep->nbytes) &&
+ (local_off.length <= (rep->nbytes - local_off.position)))
{
bits = allbits;
allbits += local_off.length;
--
1.7.10
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