[PATCH 4.4 42/54] AX.25: Prevent integer overflows in connect and sendmsg

[Greg Kroah-Hartman]

From: Dan Carpenter <dan.carpen...@oracle.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.carpen...@oracle.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.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
@@ -1192,6 +1192,7 @@ 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;