From: Frank Lichtenheld <frank@lichtenheld.com>
Date: Wed, 17 Jan 2024 09:17:11 +0000 (+0100)
Subject: NTLM: add length check to add_security_buffer
X-Git-Tag: v2.6.9~14
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7a9670dfe95da691937c608b2d3a3b939f7a4d45;p=thirdparty%2Fopenvpn.git

NTLM: add length check to add_security_buffer

Especially ntlmv2_response can be very big, so make sure
we not do exceed the size of the phase3 buffer.

Change-Id: Icea931d29e3e504e23e045539b21013b42172664
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20240117091711.5366-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg28042.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
---

diff --git a/src/openvpn/ntlm.c b/src/openvpn/ntlm.c
index 2e7721415..2b735ecda 100644
--- a/src/openvpn/ntlm.c
+++ b/src/openvpn/ntlm.c
@@ -167,8 +167,13 @@ unicodize(char *dst, const char *src)
 
 static void
 add_security_buffer(int sb_offset, void *data, int length,
-                    unsigned char *msg_buf, int *msg_bufpos)
+                    unsigned char *msg_buf, int *msg_bufpos, size_t msg_bufsize)
 {
+    if (*msg_bufpos + length > msg_bufsize)
+    {
+        msg(M_WARN, "NTLM: security buffer too big for message buffer");
+        return;
+    }
     /* Adds security buffer data to a message and sets security buffer's
      * offset and length */
     msg_buf[sb_offset] = (unsigned char)length;
@@ -396,20 +401,20 @@ ntlm_phase_3(const struct http_proxy_info *p, const char *phase_2,
     if (ntlmv2_enabled)      /* NTLMv2 response */
     {
         add_security_buffer(0x14, ntlmv2_response, ntlmv2_blob_size + 16,
-                            phase3, &phase3_bufpos);
+                            phase3, &phase3_bufpos, sizeof(phase3));
     }
     else       /* NTLM response */
     {
-        add_security_buffer(0x14, ntlm_response, 24, phase3, &phase3_bufpos);
+        add_security_buffer(0x14, ntlm_response, 24, phase3, &phase3_bufpos, sizeof(phase3));
     }
 
     /* username in ascii */
     add_security_buffer(0x24, username, strlen(username), phase3,
-                        &phase3_bufpos);
+                        &phase3_bufpos, sizeof(phase3));
 
     /* Set domain. If <domain> is empty, default domain will be used
      * (i.e. proxy's domain) */
-    add_security_buffer(0x1c, domain, strlen(domain), phase3, &phase3_bufpos);
+    add_security_buffer(0x1c, domain, strlen(domain), phase3, &phase3_bufpos, sizeof(phase3));
 
     /* other security buffers will be empty */
     phase3[0x10] = phase3_bufpos;     /* lm not used */