--- /dev/null
+From: Jeremy Harris <jgh146exb@wizmail.org>
+Date: Fri, 24 Nov 2017 20:22:33 +0000
+Subject: Avoid release of store if there have been later allocations. Bug
+ 2199
+Origin: https://git.exim.org/exim.git/commit/4090d62a4b25782129cc1643596dc2f6e8f63bde
+Bug: https://bugs.exim.org/show_bug.cgi?id=2199
+Bug-Debian: https://bugs.debian.org/882648
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-16943
+
+---
+diff --git a/src/receive.c b/src/receive.c
+index 95cf13e1..20672dbe 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;
+ }
+ }
+--
+2.15.0
+