Do proper input validation for libXfont. This is for CVE-2011-2895.

Feature safe:	yes

2 files changed, 104 insertions, 0 deletions

diff --git a/x11-fonts/libXfont/Makefile b/x11-fonts/libXfont/Makefile
index 12f4a06c16ad..90945a8b8916 100644
--- a/x11-fonts/libXfont/Makefile
+++ b/x11-fonts/libXfont/Makefile
@@ -7,6 +7,7 @@
 
 PORTNAME=	libXfont
 PORTVERSION=	1.4.4
+PORTREVISION=	1
 PORTEPOCH=	1
 CATEGORIES=	x11-fonts
 
diff --git a/x11-fonts/libXfont/files/patch-src_fontfile_decompress.c b/x11-fonts/libXfont/files/patch-src_fontfile_decompress.c
new file mode 100644
index 000000000000..1cfa1fa62235
--- /dev/null
+++ b/x11-fonts/libXfont/files/patch-src_fontfile_decompress.c
@@ -0,0 +1,103 @@
+From bd48ad11fd11412c62c3ac8ed5d52c4f10a985aa Mon Sep 17 00:00:00 2001
+From: Joerg Sonnenberger <joerg@britannica.bec.de>
+Date: Sun, 21 Aug 2011 16:51:53 +0000
+Subject: Do proper input validation to fix for CVE-2011-2895.
+
+It ensures that all valid input can be decompressed, checks that the
+overflow conditions doesn't happen and generally tightens the
+validation of the LZW stream and doesn't pessimize the inner loop for
+no good reason. It's derived from a change in libarchive from 2004.
+
+Signed-off-by: Matthieu Herrb <matthieu.herrb@laas.fr>
+Reviewed-by: Tomas Hoger <thoger@redhat.com>
+---
+diff --git a/src/fontfile/decompress.c b/src/fontfile/decompress.c
+index 0f28c3f..6405d76 100644
+--- src/fontfile/decompress.c
++++ src/fontfile/decompress.c
+@@ -97,7 +97,7 @@ static char_type magic_header[] = { "\037\235" };	/* 1F 9D */
+ #define FIRST	257	/* first free entry */
+ #define	CLEAR	256	/* table clear output code */
+ 
+-#define STACK_SIZE  8192
++#define STACK_SIZE  65300
+ 
+ typedef struct _compressedFILE {
+     BufFilePtr	    file;
+@@ -178,14 +178,12 @@ BufFilePushCompressed (BufFilePtr f)
+ 	file->tab_suffix[code] = (char_type) code;
+     }
+     file->free_ent = ((file->block_compress) ? FIRST : 256 );
++    file->oldcode = -1;
+     file->clear_flg = 0;
+     file->offset = 0;
+     file->size = 0;
+     file->stackp = file->de_stack;
+     bzero(file->buf, BITS);
+-    file->finchar = file->oldcode = getcode (file);
+-    if (file->oldcode != -1)
+-	*file->stackp++ = file->finchar;
+     return BufFileCreate ((char *) file,
+ 			  BufCompressedFill,
+ 			  0,
+@@ -230,9 +228,6 @@ BufCompressedFill (BufFilePtr f)
+ 	if (buf == bufend)
+ 	    break;
+ 
+-	if (oldcode == -1)
+-	    break;
+-
+ 	code = getcode (file);
+ 	if (code == -1)
+ 	    break;
+@@ -241,26 +236,34 @@ BufCompressedFill (BufFilePtr f)
+ 	    for ( code = 255; code >= 0; code-- )
+ 	    	file->tab_prefix[code] = 0;
+ 	    file->clear_flg = 1;
+-	    file->free_ent = FIRST - 1;
+-	    if ( (code = getcode (file)) == -1 )	/* O, untimely death! */
+-	    	break;
++	    file->free_ent = FIRST;
++	    oldcode = -1;
++	    continue;
+     	}
+     	incode = code;
+     	/*
+      	 * Special case for KwKwK string.
+      	 */
+     	if ( code >= file->free_ent ) {
++	    if ( code > file->free_ent || oldcode == -1 ) {
++		/* Bad stream. */
++		return BUFFILEEOF;
++	    }
+ 	    *stackp++ = finchar;
+ 	    code = oldcode;
+     	}
++	/*
++	 * The above condition ensures that code < free_ent.
++	 * The construction of tab_prefixof in turn guarantees that
++	 * each iteration decreases code and therefore stack usage is
++	 * bound by 1 << BITS - 256.
++	 */
+ 
+     	/*
+      	 * Generate output characters in reverse order
+      	 */
+     	while ( code >= 256 )
+     	{
+-	    if (stackp - de_stack >= STACK_SIZE - 1)
+-		return BUFFILEEOF;
+ 	    *stackp++ = file->tab_suffix[code];
+ 	    code = file->tab_prefix[code];
+     	}
+@@ -270,7 +273,7 @@ BufCompressedFill (BufFilePtr f)
+     	/*
+      	 * Generate the new entry.
+      	 */
+-    	if ( (code=file->free_ent) < file->maxmaxcode ) {
++    	if ( (code=file->free_ent) < file->maxmaxcode && oldcode != -1) {
+ 	    file->tab_prefix[code] = (unsigned short)oldcode;
+ 	    file->tab_suffix[code] = finchar;
+ 	    file->free_ent = code+1;
+--
+cgit v0.9.0.2-2-gbebe