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>
diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
index 6d9c58e..d1c16bb 100644
--- a/net/netrom/af_netrom.c
+++ b/net/netrom/af_netrom.c
@@ -1086,7 +1086,11 @@
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;