linux-kernel - [PATCH 4.19 11/17] AX.25: Prevent integer overflows in connect and sendmsg

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Message-Id: <20200730074421.011274744@linuxfoundation.org>
Date:   Thu, 30 Jul 2020 10:04:37 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.19 11/17] AX.25: Prevent integer overflows in connect and sendmsg

From: Dan Carpenter <dan.carpenter@...cle.com>

[ Upstream commit 17ad73e941b71f3bec7523ea4e9cbc3752461c2d ]

We recently added some bounds checking in ax25_connect() and
ax25_sendmsg() and we so we removed the AX25_MAX_DIGIS checks because
they were no longer required.

Unfortunately, I believe they are required to prevent integer overflows
so I have added them back.

Fixes: 8885bb0621f0 ("AX.25: Prevent out-of-bounds read in ax25_sendmsg()")
Fixes: 2f2a7ffad5c6 ("AX.25: Fix out-of-bounds read in ax25_connect()")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ax25/af_ax25.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1191,6 +1191,7 @@ static int __must_check ax25_connect(str
 	    fsa->fsa_ax25.sax25_ndigis != 0) {
 		/* Valid number of digipeaters ? */
 		if (fsa->fsa_ax25.sax25_ndigis < 1 ||
+		    fsa->fsa_ax25.sax25_ndigis > AX25_MAX_DIGIS ||
 		    addr_len < sizeof(struct sockaddr_ax25) +
 		    sizeof(ax25_address) * fsa->fsa_ax25.sax25_ndigis) {
 			err = -EINVAL;
@@ -1512,7 +1513,9 @@ static int ax25_sendmsg(struct socket *s
 			struct full_sockaddr_ax25 *fsa = (struct full_sockaddr_ax25 *)usax;
 
 			/* Valid number of digipeaters ? */
-			if (usax->sax25_ndigis < 1 || addr_len < sizeof(struct sockaddr_ax25) +
+			if (usax->sax25_ndigis < 1 ||
+			    usax->sax25_ndigis > AX25_MAX_DIGIS ||
+			    addr_len < sizeof(struct sockaddr_ax25) +
 			    sizeof(ax25_address) * usax->sax25_ndigis) {
 				err = -EINVAL;
 				goto out;