community/exim: security fix (CVE-2020-12783)

fixes #11556

1 files changed, 59 insertions, 0 deletions

diff --git a/community/exim/CVE-2020-12783-2.patch b/community/exim/CVE-2020-12783-2.patch
new file mode 100644
index 00000000000..7f1e825d95c
--- /dev/null
+++ b/community/exim/CVE-2020-12783-2.patch
@@ -0,0 +1,59 @@
+From 5a41d2c2cd2b28a0d1aea21edeaea02bd6db4984 Mon Sep 17 00:00:00 2001
+From: Jeremy Harris <jgh146exb@wizmail.org>
+Date: Wed, 6 May 2020 22:31:25 +0100
+Subject: [PATCH 45/46] Rework SPA fix to avoid overflows.  Bug 2571
+
+Amends: 6a7edbf660
+(cherry picked from commit a04174dc2a84ae1008c23b6a7109e7fa3fb7b8b0)
+---
+ src/auths/spa.c | 13 +++++++++----
+ 1 file changed, 9 insertions(+), 4 deletions(-)
+
+diff --git a/src/auths/spa.c b/src/auths/spa.c
+index ed9aff23b..4e3aef808 100644
+--- a/src/auths/spa.c
++++ b/src/auths/spa.c
+@@ -140,6 +140,7 @@ SPAAuthResponse  response;
+ SPAAuthResponse  *responseptr = &response;
+ uschar msgbuf[2048];
+ uschar *clearpass, *s;
++unsigned off;
+ 
+ /* send a 334, MS Exchange style, and grab the client's request,
+ unless we already have it via an initial response. */
+@@ -194,10 +195,13 @@ that causes failure if the size of msgbuf is exceeded. ****/
+ 
+   {
+   int i;
+-  char *p = ((char*)responseptr) + IVAL(&responseptr->uUser.offset,0);
++  char * p;
+   int len = SVAL(&responseptr->uUser.len,0)/2;
+ 
+-  if (p + len*2 >= CS (responseptr+1))
++  if (  (off = IVAL(&responseptr->uUser.offset,0)) >= sizeof(SPAAuthResponse)
++     || len >= sizeof(responseptr->buffer)/2
++     || (p = (CS responseptr) + off) + len*2 >= CS (responseptr+1)
++     )
+     {
+     DEBUG(D_auth)
+       debug_printf("auth_spa_server(): bad uUser spec in response\n");
+@@ -252,13 +256,14 @@ spa_smb_nt_encrypt (clearpass, challenge.challengeData, ntRespData);
+ 
+ /* compare NT hash (LM may not be available) */
+ 
+-s = (US responseptr) + IVAL(&responseptr->ntResponse.offset,0);
+-if (s + 24 >= US (responseptr+1))
++off = IVAL(&responseptr->ntResponse.offset,0);
++if (off >= sizeof(SPAAuthResponse) - 24)
+   {
+   DEBUG(D_auth)
+     debug_printf("auth_spa_server(): bad ntRespData spec in response\n");
+   return FAIL;
+   }
++s = (US responseptr) + off;
+ 
+ if (memcmp(ntRespData, s, 24) == 0)
+   return auth_check_serv_cond(ablock);	/* success. we have a winner. */
+-- 
+2.26.2
+