af_rose/x25: Sanity check the maximum user frame size

Otherwise we can wrap the sizes and end up sending garbage.

Closes #10423

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 15 insertions, 1 deletions

diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
index 6d9c58ec56ac..d1c16bbee932 100644
--- a/net/netrom/af_netrom.c
+++ b/net/netrom/af_netrom.c
@@ -1086,7 +1086,11 @@ static int nr_sendmsg(struct kiocb *iocb, struct socket *sock,
 
         SOCK_DEBUG(sk, "NET/ROM: sendto: Addresses built.\n");
 
-        /* Build a packet */
+        /* Build a packet - the conventional user limit is 236 bytes. We can
+           do ludicrously large NetROM frames but must not overflow */
+        if (len > 65536)
+                return -EMSGSIZE;
+
         SOCK_DEBUG(sk, "NET/ROM: sendto: building packet.\n");
         size = len + NR_NETWORK_LEN + NR_TRANSPORT_LEN;
 
diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
index 650139626581..0f36e8d59b29 100644
--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -1124,6 +1124,10 @@ static int rose_sendmsg(struct kiocb *iocb, struct socket *sock,
 
         /* Build a packet */
         SOCK_DEBUG(sk, "ROSE: sendto: building packet.\n");
+        /* Sanity check the packet size */
+        if (len > 65535)
+                return -EMSGSIZE;
+
         size = len + AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN;
 
         if ((skb = sock_alloc_send_skb(sk, size, msg->msg_flags & MSG_DONTWAIT, &err)) == NULL)
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 9ca17b1ce52e..ed80af8ca5fb 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -1035,6 +1035,12 @@ static int x25_sendmsg(struct kiocb *iocb, struct socket *sock,
                 sx25.sx25_addr   = x25->dest_addr;
         }
 
+        /* Sanity check the packet size */
+        if (len > 65535) {
+                rc = -EMSGSIZE;
+                goto out;
+        }
+
         SOCK_DEBUG(sk, "x25_sendmsg: sendto: Addresses built.\n");
 
         /* Build a packet */