Re: cracklib: Fix buffer overflow

[Efraim Flashner <efraim@flashner.co.il>]

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On Thu, Sep 15, 2016 at 11:36:46AM -0400, Leo Famulari wrote:
> This patch cherry-picks an upstream commit to fix a buffer overflow in
> cracklib. Please see the patch file for more information about the bug.

> From 62f8f1763ba1766e92e8dc05686bd9353eaf2ad5 Mon Sep 17 00:00:00 2001
> From: Leo Famulari <leo@famulari.name>
> Date: Thu, 15 Sep 2016 11:34:49 -0400
> Subject: [PATCH] gnu: cracklib: Fix buffer overflow.
> 
> * gnu/packages/patches/cracklib-fix-buffer-overflow.patch: New file.
> * gnu/local.mk (dist_patch_DATA): Add it.
> * gnu/packages/password-utils.scm (cracklib)[source]: Use it.
> ---
>  gnu/local.mk                                       |  1 +
>  gnu/packages/password-utils.scm                    |  3 +-
>  .../patches/cracklib-fix-buffer-overflow.patch     | 39 ++++++++++++++++++++++
>  3 files changed, 42 insertions(+), 1 deletion(-)
>  create mode 100644 gnu/packages/patches/cracklib-fix-buffer-overflow.patch
> 
> diff --git a/gnu/local.mk b/gnu/local.mk
> index a7006cb..ab052af 100644
> --- a/gnu/local.mk
> +++ b/gnu/local.mk
> @@ -473,6 +473,7 @@ dist_patch_DATA =						\
>    %D%/packages/patches/cpio-CVE-2016-2037.patch			\
>    %D%/packages/patches/cpufrequtils-fix-aclocal.patch		\
>    %D%/packages/patches/cracklib-CVE-2016-6318.patch		\
> +  %D%/packages/patches/cracklib-fix-buffer-overflow.patch	\
>    %D%/packages/patches/crda-optional-gcrypt.patch		\
>    %D%/packages/patches/crossmap-allow-system-pysam.patch	\
>    %D%/packages/patches/csound-header-ordering.patch		\
> diff --git a/gnu/packages/password-utils.scm b/gnu/packages/password-utils.scm
> index 7288da6..40ed933 100644
> --- a/gnu/packages/password-utils.scm
> +++ b/gnu/packages/password-utils.scm
> @@ -160,7 +160,8 @@ and vice versa.")
>                (uri (string-append "https://github.com/cracklib/cracklib/"
>                                    "releases/download/" name "-" version "/"
>                                    name "-" version ".tar.gz"))
> -              (patches (search-patches "cracklib-CVE-2016-6318.patch"))
> +              (patches (search-patches "cracklib-CVE-2016-6318.patch"
> +                                       "cracklib-fix-buffer-overflow.patch"))
>                (sha256
>                 (base32
>                  "0hrkb0prf7n92w6rxgq0ilzkk6rkhpys2cfqkrbzswp27na7dkqp"))))
> diff --git a/gnu/packages/patches/cracklib-fix-buffer-overflow.patch b/gnu/packages/patches/cracklib-fix-buffer-overflow.patch
> new file mode 100644
> index 0000000..b1c990f
> --- /dev/null
> +++ b/gnu/packages/patches/cracklib-fix-buffer-overflow.patch
> @@ -0,0 +1,39 @@
> +Fix buffer overflow processing long words in Mangle().
> +
> +Patch adpated from upstream commit, omitting changes to 'NEWS':
> +
> +https://github.com/cracklib/cracklib/commit/33d7fa4585247cd2247a1ffa032ad245836c6edb
> +
> +From 33d7fa4585247cd2247a1ffa032ad245836c6edb Mon Sep 17 00:00:00 2001
> +From: Jan Dittberner <jan@dittberner.info>
> +Date: Thu, 25 Aug 2016 17:17:53 +0200
> +Subject: [PATCH] Fix a buffer overflow processing long words
> +
> +A buffer overflow processing long words has been discovered. This commit
> +applies the patch from
> +https://build.opensuse.org/package/view_file/Base:System/cracklib/0004-overflow-processing-long-words.patch
> +by Howard Guo.
> +
> +See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=835386 and
> +http://www.openwall.com/lists/oss-security/2016/08/23/8
> +---
> + src/NEWS        | 1 +
> + src/lib/rules.c | 5 ++---
> + 2 files changed, 3 insertions(+), 3 deletions(-)
> +
> +diff --git a/src/lib/rules.c b/src/lib/rules.c
> +index d193cc0..3a2aa46 100644
> +--- a/lib/rules.c
> ++++ b/lib/rules.c
> +@@ -434,9 +434,8 @@ Mangle(input, control)		/* returns a pointer to a controlled Mangle */
> + {
> +     int limit;
> +     register char *ptr;
> +-    static char area[STRINGSIZE];
> +-    char area2[STRINGSIZE];
> +-    area[0] = '\0';
> ++    static char area[STRINGSIZE * 2] = {0};
> ++    char area2[STRINGSIZE * 2] = {0};
> +     strcpy(area, input);
> + 
> +     for (ptr = control; *ptr; ptr++)
> -- 
> 2.10.0
> 

not having looked at the full source of lib/rules.c, is there a maximum
value to STRINGSIZE to make sure STRINGSIZE * 2 doesn't wrap around?


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Efraim Flashner   <efraim@flashner.co.il>   אפרים פלשנר
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