gnu: exim: Fix CVE-2017-16943.

* gnu/packages/patches/exim-CVE-2017-16943.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/mail.scm (exim)[source]: Use it.

gnu/local.mk

@@ -614,6 +614,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/erlang-man-path.patch			\
   %D%/packages/patches/eudev-rules-directory.patch		\
   %D%/packages/patches/evilwm-lost-focus-bug.patch		\
+  %D%/packages/patches/exim-CVE-2017-16943.patch		\
   %D%/packages/patches/exim-CVE-2017-1000369.patch		\
   %D%/packages/patches/exiv2-CVE-2017-14860.patch		\
   %D%/packages/patches/exiv2-CVE-2017-14859-14862-14864.patch	\

gnu/packages/mail.scm

@@ -1042,7 +1042,8 @@ delivery.")
                                  version ".tar.bz2")
                   (string-append "ftp://ftp.exim.org/pub/exim/exim4/old/exim-"
                                  version ".tar.bz2")))
-       (patches (search-patches "exim-CVE-2017-1000369.patch"))
+       (patches (search-patches "exim-CVE-2017-16943.patch"
+                                "exim-CVE-2017-1000369.patch"))
        (sha256
         (base32
          "1c0syp7yxngmq7y8vqsrvijinzin5m941vn0ljihdfld7kh2wbwi"))))

gnu/packages/patches/exim-CVE-2017-16943.patch

@@ -0,0 +1,65 @@
+Fix CVE-2017-16943:
+
+https://bugs.exim.org/show_bug.cgi?id=2199
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-16943
+
+Patch copied from upstream source repository:
+
+https://git.exim.org/exim.git/commit/4090d62a4b25782129cc1643596dc2f6e8f63bde
+
+From 4090d62a4b25782129cc1643596dc2f6e8f63bde Mon Sep 17 00:00:00 2001
+From: Jeremy Harris <jgh146exb@wizmail.org>
+Date: Fri, 24 Nov 2017 20:22:33 +0000
+Subject: [PATCH] Avoid release of store if there have been later allocations. 
+ Bug 2199
+
+---
+ doc/doc-txt/ChangeLog | 4 ++++
+ src/src/receive.c     | 7 ++++---
+ 2 files changed, 8 insertions(+), 3 deletions(-)
+
+#diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
+#index e937ba2..a2d9339 100644
+#--- a/doc/doc-txt/ChangeLog
+#+++ b/doc/doc-txt/ChangeLog
+#@@ -59,6 +59,10 @@ JH/30 Fix a logging bug on aarch64: an unsafe routine was previously used for
+#       connection in response to HELO" was logged instead of the actual 4xx
+#       error for the HELO.
+# 
+#+JH/34 Bug 2199: fix a use-after-free while reading smtp input for header lines.
+#+      A crafted sequence of BDAT commands could result in in-use memory beeing
+#+      freed.
+#+
+# 
+ Exim version 4.89
+ -----------------
+diff --git a/src/src/receive.c b/src/src/receive.c
+index 95cf13e..20672db 100644
+--- a/src/receive.c
++++ b/src/receive.c
+@@ -1772,8 +1772,8 @@ for (;;)
+   (and sometimes lunatic messages can have ones that are 100s of K long) we
+   call store_release() for strings that have been copied - if the string is at
+   the start of a block (and therefore the only thing in it, because we aren't
+-  doing any other gets), the block gets freed. We can only do this because we
+-  know there are no other calls to store_get() going on. */
++  doing any other gets), the block gets freed. We can only do this release if
++  there were no allocations since the once that we want to free. */
+ 
+   if (ptr >= header_size - 4)
+     {
+@@ -1782,9 +1782,10 @@ for (;;)
+     header_size *= 2;
+     if (!store_extend(next->text, oldsize, header_size))
+       {
++      BOOL release_ok = store_last_get[store_pool] == next->text;
+       uschar *newtext = store_get(header_size);
+       memcpy(newtext, next->text, ptr);
+-      store_release(next->text);
++      if (release_ok) store_release(next->text);
+       next->text = newtext;
+       }
+     }
+-- 
+1.9.1
+