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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
|
