From 2351c83a77a478b49cba6beb2ad386835e264744 Mon Sep 17 00:00:00 2001
From: Alan Coopersmith <alan.coopersmith@oracle.com>
Date: Fri, 6 Mar 2015 22:54:58 -0800
Subject: bdfReadCharacters: ensure metrics fit into xCharInfo struct
 [CVE-2015-1804]

We use 32-bit ints to read from the bdf file, but then try to stick
into a 16-bit int in the xCharInfo struct, so make sure they won't
overflow that range.

Found by afl-1.24b.

v2: Verify that additions won't overflow 32-bit int range either.
v3: As Julien correctly observes, the previous check for bh & bw not
    being < 0 reduces the number of cases we need to check for overflow.

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Julien Cristau <jcristau@debian.org>

diff --git a/src/bitmap/bdfread.c b/src/bitmap/bdfread.c
index 1b29b81..a0ace8f 100644
--- a/src/bitmap/bdfread.c
+++ b/src/bitmap/bdfread.c
@@ -62,8 +62,16 @@ from The Open Group.
 
 #if HAVE_STDINT_H
 #include <stdint.h>
-#elif !defined(INT32_MAX)
-#define INT32_MAX 0x7fffffff
+#else
+# ifndef INT32_MAX
+#  define INT32_MAX 0x7fffffff
+# endif
+# ifndef INT16_MAX
+#  define INT16_MAX 0x7fff
+# endif
+# ifndef INT16_MIN
+#  define INT16_MIN (0 - 0x8000)
+# endif
 #endif
 
 #define INDICES 256
@@ -417,6 +425,12 @@ bdfReadCharacters(FontFilePtr file, FontPtr pFont, bdfFileState *pState,
 	    bdfError("DWIDTH y value must be zero\n");
 	    goto BAILOUT;
 	}
+	/* xCharInfo metrics are stored as INT16 */
+	if ((wx < 0) || (wx > INT16_MAX)) {
+	    bdfError("character '%s' has out of range width, %d\n",
+		     charName, wx);
+	    goto BAILOUT;
+	}
 	line = bdfGetLine(file, lineBuf, BDFLINELEN);
 	if ((!line) || (sscanf((char *) line, "BBX %d %d %d %d", &bw, &bh, &bl, &bb) != 4)) {
 	    bdfError("bad 'BBX'\n");
@@ -427,6 +441,14 @@ bdfReadCharacters(FontFilePtr file, FontPtr pFont, bdfFileState *pState,
 		     charName, bw, bh);
 	    goto BAILOUT;
 	}
+	/* xCharInfo metrics are read as int, but stored as INT16 */
+	if ((bl > INT16_MAX) || (bl < INT16_MIN) ||
+	    (bb > INT16_MAX) || (bb < INT16_MIN) ||
+	    (bw > (INT16_MAX - bl)) || (bh > (INT16_MAX - bb))) {
+	    bdfError("character '%s' has out of range metrics, %d %d %d %d\n",
+		     charName, bl, (bl+bw), (bh+bb), -bb);
+	    goto BAILOUT;
+	}
 	line = bdfGetLine(file, lineBuf, BDFLINELEN);
 	if ((line) && (bdfIsPrefix(line, "ATTRIBUTES"))) {
 	    for (p = line + strlen("ATTRIBUTES ");
-- 
cgit v0.10.2

