Unverified Commit 39df4073 authored by Daniel Gustafsson's avatar Daniel Gustafsson Committed by Daniel Stenberg
Browse files

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.

Bug: https://curl.haxx.se/docs/CVE-2019-3823.html
Reported-by: Brian Carpenter (Geeknik Labs)
CVE-2019-3823
parent 50c94842

lib/smtp.c

+6 −2
Original line number Original line Diff line number Diff line
@@ -5,7 +5,7 @@ 
 *                            | (__| |_| |  _ <| |___

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *                             \___|\___/|_| \_\_____|

 *

 *

 * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.

 * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 *

 * This software is licensed as described in the file COPYING, which

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * you should have received as part of this distribution. The terms
@@ -207,8 +207,12 @@ static bool smtp_endofresp(struct connectdata *conn, char *line, size_t len, 
     Section 4. Examples of RFC-4954 but some e-mail servers ignore this and

     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. */

     only send the response code instead as per Section 4.2. */

  if(line[3] == ' ' || len == 5) {

  if(line[3] == ' ' || len == 5) {

    char tmpline[6];



    result = TRUE;

    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 */

    /* Make sure real server never sends internal value */

    if(*resp == 1)

    if(*resp == 1)