Bug 731246 (CVE-2011-2939)

Perl bundles `Encode' module (http://search.cpan.org/~dankogai/Encode/) that contains `Unicode.xs' file where a heap overflow bug has been fixed recently (http://cpansearch.perl.org/src/DANKOGAI/Encode-2.44/Changes):

$Revision: 2.44 $ $Date: 2011/08/09 07:49:44 $
! Unicode/Unicode.xs
  Addressed the following:
    Date: Fri, 22 Jul 2011 13:58:43 +0200
    From: Robert Zacek <zacek>
    To: perl5-security-report
    Subject: Unicode.xs!decode_xs n-byte heap-overflow

The patch has been merged into perl development tree (http://perl5.git.perl.org/perl.git/commitdiff/e46d973584785af1f445c4dedbee4243419cb860#patch5):


diff --git a/cpan/Encode/Unicode/Unicode.xs b/cpan/Encode/Unicode/Unicode.xs

index 16f4cd1..039f155 100644 (file)


--- a/cpan/Encode/Unicode/Unicode.xs
+++ b/cpan/Encode/Unicode/Unicode.xs
@@ -1,5 +1,5 @@
 /*
- $Id: Unicode.xs,v 2.7 2010/12/31 22:48:48 dankogai Exp $
+ $Id: Unicode.xs,v 2.8 2011/08/09 07:49:44 dankogai Exp dankogai $
  */
 
 #define PERL_NO_GET_CONTEXT
@@ -256,7 +256,10 @@ CODE:
               This prevents allocating too much in the rogue case of a large
               input consisting initially of long sequence uft8-byte unicode
               chars followed by single utf8-byte chars. */
-           STRLEN remaining = (e - s)/usize;
+            /* +1 
+               fixes  Unicode.xs!decode_xs n-byte heap-overflow
+              */
+           STRLEN remaining = (e - s)/usize + 1; /* +1 to avoid the leak */
            STRLEN max_alloc = remaining + (8*1024*1024);
            STRLEN est_alloc = remaining * UTF8_MAXLEN;
            STRLEN newlen = SvLEN(result) + /* min(max_alloc, est_alloc) */

Debian has applied the fix for Perl 5.12 and 5.14 versions (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=637376) so far but recognized the bug in all Perl releases since 5.10.0.

No reproducer or other details are known now. This flaw is public.
Non-replied question has been post to perl-ports mailing list (http://permalink.gmane.org/gmane.comp.lang.perl.perl5.porters/98004).