From 8d5c7813061dfa0b187500dfe3aeea7a28181c13 Mon Sep 17 00:00:00 2001
From: Mark Johnston <markj@FreeBSD.org>
Date: Tue, 25 May 2021 13:59:09 -0400
Subject: [PATCH] libradius: Fix input validation bugs

Approved by:	so
Security:	FreeBSD-SA-21:12.libradius
Security:	CVE-2021-29629
MFC after:	now
Sponsored by:	The FreeBSD Foundation
---
 lib/libradius/radlib.c | 54 ++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 15 deletions(-)

diff --git a/lib/libradius/radlib.c b/lib/libradius/radlib.c
index e01c486a1ba6..18aee8b53024 100644
--- a/lib/libradius/radlib.c
+++ b/lib/libradius/radlib.c
@@ -187,7 +187,7 @@ is_valid_response(struct rad_handle *h, int srv,
 	MD5_CTX ctx;
 	unsigned char md5[MD5_DIGEST_LENGTH];
 	const struct rad_server *srvp;
-	int len;
+	int alen, len;
 #ifdef WITH_SSL
 	HMAC_CTX *hctx;
 	u_char resp[MSGSIZE], md[EVP_MAX_MD_SIZE];
@@ -206,8 +206,8 @@ is_valid_response(struct rad_handle *h, int srv,
 	/* Check the message length */
 	if (h->in_len < POS_ATTRS)
 		return 0;
-	len = h->in[POS_LENGTH] << 8 | h->in[POS_LENGTH+1];
-	if (len > h->in_len)
+	len = (h->in[POS_LENGTH] << 8) | h->in[POS_LENGTH + 1];
+	if (len < POS_ATTRS || len > h->in_len)
 		return 0;
 
 	/* Check the response authenticator */
@@ -233,9 +233,16 @@ is_valid_response(struct rad_handle *h, int srv,
 		/* Search and verify the Message-Authenticator */
 		hctx = HMAC_CTX_new();
 		while (pos < len - 2) {
-
 			if (h->in[pos] == RAD_MESSAGE_AUTHENTIC) {
-				/* zero fill the Message-Authenticator */
+				if (h->in[pos + 1] != MD5_DIGEST_LENGTH + 2) {
+					HMAC_CTX_free(hctx);
+					return 0;
+				}
+				if (len - pos < MD5_DIGEST_LENGTH + 2) {
+					HMAC_CTX_free(hctx);
+					return 0;
+				}
+
 				memset(&resp[pos + 2], 0, MD5_DIGEST_LENGTH);
 
 				HMAC_Init_ex(hctx, srvp->secret,
@@ -255,7 +262,12 @@ is_valid_response(struct rad_handle *h, int srv,
 				}
 				break;
 			}
-			pos += h->in[pos + 1];
+			alen = h->in[pos + 1];
+			if (alen < 2) {
+				HMAC_CTX_free(hctx);
+				return 0;
+			}
+			pos += alen;
 		}
 		HMAC_CTX_free(hctx);
 	}
@@ -272,7 +284,7 @@ is_valid_request(struct rad_handle *h)
 	MD5_CTX ctx;
 	unsigned char md5[MD5_DIGEST_LENGTH];
 	const struct rad_server *srvp;
-	int len;
+	int alen, len;
 #ifdef WITH_SSL
 	HMAC_CTX *hctx;
 	u_char resp[MSGSIZE], md[EVP_MAX_MD_SIZE];
@@ -285,8 +297,8 @@ is_valid_request(struct rad_handle *h)
 	/* Check the message length */
 	if (h->in_len < POS_ATTRS)
 		return (0);
-	len = h->in[POS_LENGTH] << 8 | h->in[POS_LENGTH+1];
-	if (len > h->in_len)
+	len = (h->in[POS_LENGTH] << 8) | h->in[POS_LENGTH + 1];
+	if (len < POS_ATTRS || len > h->in_len)
 		return (0);
 
 	if (h->in[POS_CODE] != RAD_ACCESS_REQUEST) {
@@ -307,7 +319,18 @@ is_valid_request(struct rad_handle *h)
 	pos = POS_ATTRS;
 	hctx = HMAC_CTX_new();
 	while (pos < len - 2) {
+		alen = h->in[pos + 1];
+		if (alen < 2)
+			return (0);
 		if (h->in[pos] == RAD_MESSAGE_AUTHENTIC) {
+			if (len - pos < MD5_DIGEST_LENGTH + 2) {
+				HMAC_CTX_free(hctx);
+				return (0);
+			}
+			if (alen < MD5_DIGEST_LENGTH + 2) {
+				HMAC_CTX_free(hctx);
+				return (0);
+			}
 			memcpy(resp, h->in, MSGSIZE);
 			/* zero fill the Request-Authenticator */
 			if (h->in[POS_CODE] != RAD_ACCESS_REQUEST)
@@ -327,7 +350,7 @@ is_valid_request(struct rad_handle *h)
 			}
 			break;
 		}
-		pos += h->in[pos + 1];
+		pos += alen;
 	}
 	HMAC_CTX_free(hctx);
 #endif
@@ -929,9 +952,9 @@ rad_cvt_string(const void *data, size_t len)
  * returns -1.
  */
 int
-rad_get_attr(struct rad_handle *h, const void **value, size_t *len)
+rad_get_attr(struct rad_handle *h, const void **value, size_t *lenp)
 {
-	int type;
+	int len, type;
 
 	if (h->in_pos >= h->in_len)
 		return 0;
@@ -940,13 +963,14 @@ rad_get_attr(struct rad_handle *h, const void **value, size_t *len)
 		return -1;
 	}
 	type = h->in[h->in_pos++];
-	*len = h->in[h->in_pos++] - 2;
-	if (h->in_pos + (int)*len > h->in_len) {
+	len = h->in[h->in_pos++];
+	if (len < 2 || h->in_pos + len > h->in_len) {
 		generr(h, "Malformed attribute in response");
 		return -1;
 	}
+	*lenp = len;
 	*value = &h->in[h->in_pos];
-	h->in_pos += *len;
+	h->in_pos += len;
 	return type;
 }