[PATCH 5.4 12/19] AX.25: Prevent integer overflows in connect and sendmsg

Greg Kroah-Hartman
2020-07-30T08:05:49Z

From: Dan Carpenter <dan.carpenter@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.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@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
@@ -1188,6 +1188,7 @@ 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;
@@ -1509,7 +1510,9 @@ 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;