Import Debian changes 4.92-8+deb10u6

[hcoop/debian/exim4.git] / debian / patches / 84_18-Security-Fix-off-by-one-in-smtp-transport-read-respo.patch

From 28335a4704d8d615fd61e05ea6e435a4cd24e4df Mon Sep 17 00:00:00 2001
From: Qualys Security Advisory <qsa@qualys.com>
Date: Sun, 21 Feb 2021 22:13:18 -0800
Subject: [PATCH 18/29] Security: Fix off-by-one in smtp transport (read
 response)

Based on Heiko Schlittermann's commit 1887a160. This fixes:

1/ In src/transports/smtp.c:

2281       int n = sizeof(sx->buffer);
2282       uschar * rsp = sx->buffer;
2283
2284       if (sx->esmtp_sent && (n = Ustrlen(sx->buffer)) < sizeof(sx->buffer)/2)
2285         { rsp = sx->buffer + n + 1; n = sizeof(sx->buffer) - n; }

This should probably be either:

rsp = sx->buffer + n + 1; n = sizeof(sx->buffer) - n - 1;

or:

rsp = sx->buffer + n; n = sizeof(sx->buffer) - n;

(not sure which) to avoid an off-by-one.
---
 src/transports/smtp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/transports/smtp.c b/src/transports/smtp.c
index cc37e73f3..07b63a2aa 100644
--- a/src/transports/smtp.c
+++ b/src/transports/smtp.c
@@ -2328,8 +2328,8 @@ goto SEND_QUIT;
       int n = sizeof(sx->buffer);
       uschar * rsp = sx->buffer;
 
-      if (sx->esmtp_sent && (n = Ustrlen(sx->buffer)) < sizeof(sx->buffer)/2)
-	{ rsp = sx->buffer + n + 1; n = sizeof(sx->buffer) - n; }
+      if (sx->esmtp_sent && (n = Ustrlen(sx->buffer) + 1) < sizeof(sx->buffer)/2)
+	{ rsp = sx->buffer + n; n = sizeof(sx->buffer) - n; }
 
       if (smtp_write_command(sx, SCMD_FLUSH, "HELO %s\r\n", sx->helo_data) < 0)
 	goto SEND_FAILED;
-- 
2.30.2