Subject: [PATCH] gnu: libtasn1: Fix CVE-2018-6003.

From: Leo Famulari <[email-masked]>
Date: Sat, 10 Feb 2018 16:54:44 -0500

* gnu/packages/patches/libtasn1-CVE-2018-6003.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/tls.scm (libtasn1/fixed)[source]: Use it.
---
 gnu/local.mk                                      |  1 +
 gnu/packages/patches/libtasn1-CVE-2018-6003.patch | 73 +++++++++++++++++++++++
 gnu/packages/tls.scm                              |  3 +-
 3 files changed, 76 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/libtasn1-CVE-2018-6003.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index eb968dede..9b32e5880 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -852,6 +852,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/libssh2-fix-build-failure-with-gcrypt.patch	\
   %D%/packages/patches/libtar-CVE-2013-4420.patch 		\
   %D%/packages/patches/libtasn1-CVE-2017-10790.patch		\
+  %D%/packages/patches/libtasn1-CVE-2018-6003.patch		\
   %D%/packages/patches/libtheora-config-guess.patch		\
   %D%/packages/patches/libtiff-CVE-2016-10688.patch		\
   %D%/packages/patches/libtiff-CVE-2017-9936.patch		\
diff --git a/gnu/packages/patches/libtasn1-CVE-2018-6003.patch b/gnu/packages/patches/libtasn1-CVE-2018-6003.patch
new file mode 100644
index 000000000..3e6140518
--- /dev/null
+++ b/gnu/packages/patches/libtasn1-CVE-2018-6003.patch
@@ -0,0 +1,73 @@
+Fix CVE-2018-6003:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-6003
+https://lists.gnu.org/archive/html/help-libtasn1/2018-01/msg00000.html
+
+Patch copied from upstream source repository:
+
+https://gitlab.com/gnutls/libtasn1/commit/c593ae84cfcde8fea45787e53950e0ac71e9ca97
+
+From c593ae84cfcde8fea45787e53950e0ac71e9ca97 Mon Sep 17 00:00:00 2001
+From: Nikos Mavrogiannopoulos <[email-masked]>
+Date: Thu, 4 Jan 2018 10:52:05 +0100
+Subject: [PATCH] _asn1_decode_simple_ber: restrict the levels of recursion to 3
+
+On indefinite string decoding, setting a maximum level of recursions
+protects the BER decoder from a stack exhaustion due to large amounts
+of recursion.
+
+Signed-off-by: Nikos Mavrogiannopoulos <[email-masked]>
+---
+ lib/decoding.c | 21 +++++++++++++++++++--
+ 1 file changed, 19 insertions(+), 2 deletions(-)
+
+diff --git a/lib/decoding.c b/lib/decoding.c
+index 2240b09..0ee35d3 100644
+--- a/lib/decoding.c
++++ b/lib/decoding.c
+@@ -45,6 +45,13 @@
+ 
+ #define DECODE_FLAG_HAVE_TAG 1
+ #define DECODE_FLAG_INDEFINITE (1<<1)
++/* On indefinite string decoding, allow this maximum levels
++ * of recursion. Allowing infinite recursion, makes the BER
++ * decoder susceptible to stack exhaustion due to that recursion.
++ */
++#define DECODE_FLAG_LEVEL1 (1<<2)
++#define DECODE_FLAG_LEVEL2 (1<<3)
++#define DECODE_FLAG_LEVEL3 (1<<4)
+ 
+ #define DECR_LEN(l, s) do { \
+ 	  l -= s; \
+@@ -2216,7 +2223,8 @@ _asn1_decode_simple_ber (unsigned int etype, const unsigned char *der,
+     }
+ 
+   /* indefinite constructed */
+-  if (((dflags & DECODE_FLAG_INDEFINITE) || class == ASN1_CLASS_STRUCTURED) && ETYPE_IS_STRING(etype))
++  if ((((dflags & DECODE_FLAG_INDEFINITE) || class == ASN1_CLASS_STRUCTURED) && ETYPE_IS_STRING(etype)) &&
++      !(dflags & DECODE_FLAG_LEVEL3))
+     {
+       len_len = 1;
+ 
+@@ -2236,8 +2244,17 @@ _asn1_decode_simple_ber (unsigned int etype, const unsigned char *der,
+       do
+         {
+           unsigned tmp_len;
++          unsigned flags = DECODE_FLAG_HAVE_TAG;
++
++          if (dflags & DECODE_FLAG_LEVEL1)
++                flags |= DECODE_FLAG_LEVEL2;
++          else if (dflags & DECODE_FLAG_LEVEL2)
++		flags |= DECODE_FLAG_LEVEL3;
++	  else
++		flags |= DECODE_FLAG_LEVEL1;
+ 
+-          result = asn1_decode_simple_ber(etype, p, der_len, &out, &out_len, &tmp_len);
++          result = _asn1_decode_simple_ber(etype, p, der_len, &out, &out_len, &tmp_len,
++                                           flags);
+           if (result != ASN1_SUCCESS)
+             {
+               warn();
+--
+libgit2 0.26.0
+
diff --git a/gnu/packages/tls.scm b/gnu/packages/tls.scm
index fa58f90cb..c2123add4 100644
--- a/gnu/packages/tls.scm
+++ b/gnu/packages/tls.scm
@@ -91,7 +91,8 @@ specifications.")
     (inherit libtasn1)
     (source (origin
               (inherit (package-source libtasn1))
-              (patches (search-patches "libtasn1-CVE-2017-10790.patch"))))))
+              (patches (search-patches "libtasn1-CVE-2017-10790.patch"
+                                       "libtasn1-CVE-2018-6003.patch"))))))
 
 (define-public asn1c
   (package
-- 
2.16.1