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From d26f1025d0a0a6c602d758a2e0917759492473e9 Mon Sep 17 00:00:00 2001
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From: Daniel Gustafsson <daniel@yesql.se>
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Date: Sat, 19 Jan 2019 00:42:47 +0100
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Subject: [PATCH] smtp: avoid risk of buffer overflow in strtol
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If the incoming len 5, but the buffer does not have a termination
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after 5 bytes, the strtol() call may keep reading through the line
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buffer until is exceeds its boundary. Fix by ensuring that we are
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using a bounded read with a temporary buffer on the stack.
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Bug: https://curl.haxx.se/docs/CVE-2019-3823.html
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Reported-by: Brian Carpenter (Geeknik Labs)
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CVE-2019-3823
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Upstream-commit: 39df4073e5413fcdbb5a38da0c1ce6f1c0ceb484
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Signed-off-by: Kamil Dudka <kdudka@redhat.com>
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---
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 lib/smtp.c | 8 ++++++--
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 1 file changed, 6 insertions(+), 2 deletions(-)
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diff --git a/lib/smtp.c b/lib/smtp.c
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index ecf10a4..1b9f92d 100644
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--- a/lib/smtp.c
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+++ b/lib/smtp.c
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@@ -5,7 +5,7 @@
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  *                            | (__| |_| |  _ <| |___
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  *                             \___|\___/|_| \_\_____|
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  *
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- * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
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+ * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
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  *
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  * This software is licensed as described in the file COPYING, which
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  * you should have received as part of this distribution. The terms
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@@ -207,8 +207,12 @@ static bool smtp_endofresp(struct connectdata *conn, char *line, size_t len,
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      Section 4. Examples of RFC-4954 but some e-mail servers ignore this and
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      only send the response code instead as per Section 4.2. */
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   if(line[3] == ' ' || len == 5) {
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+    char tmpline[6];
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+
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     result = TRUE;
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-    *resp = curlx_sltosi(strtol(line, NULL, 10));
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+    memset(tmpline, '\0', sizeof(tmpline));
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+    memcpy(tmpline, line, (len == 5 ? 5 : 3));
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+    *resp = curlx_sltosi(strtol(tmpline, NULL, 10));
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     /* Make sure real server never sends internal value */
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     if(*resp == 1)
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-- 
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2.17.2
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