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From 89dd3f49e1248d7f39401ecc9eecb4e82885e629 Mon Sep 17 00:00:00 2001
From: Daniel Gustafsson <daniel@yesql.se>
Date: Sat, 19 Jan 2019 00:42:47 +0100
Subject: [PATCH 3/3] smtp: avoid risk of buffer overflow in strtol
If the incoming len 5, but the buffer does not have a termination
after 5 bytes, the strtol() call may keep reading through the line
buffer until is exceeds its boundary. Fix by ensuring that we are
using a bounded read with a temporary buffer on the stack.
Reported-by: Brian Carpenter (Geeknik Labs)
---
lib/smtp.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -255,8 +255,12 @@
Section 4. Examples of RFC-4954 but some e-mail servers ignore this and
only send the response code instead as per Section 4.2. */
if(line[3] == ' ' || len == 5) {
+ char tmpline[6];
+
result = TRUE;
- *resp = curlx_sltosi(strtol(line, NULL, 10));
+ memset(tmpline, '\0', sizeof(tmpline));
+ memcpy(tmpline, line, (len == 5 ? 5 : 3));
+ *resp = curlx_sltosi(strtol(tmpline, NULL, 10));
/* Make sure real server never sends internal value */
if(*resp == 1)
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