[PATCH] ieee802154: verify packet size before trying to allocate it

[Sasha Levin <levinsasha928-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Currently when sending data over datagram, the send function will attempt to
allocate any size passed on from the userspace.

We should make sure that this size is checked and limited. The maximum size
of an IP packet seemed like the safest limit here.

Signed-off-by: Sasha Levin <levinsasha928-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 net/ieee802154/dgram.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/net/ieee802154/dgram.c b/net/ieee802154/dgram.c
index 6fbb2ad..cf5070b 100644
--- a/net/ieee802154/dgram.c
+++ b/net/ieee802154/dgram.c
@@ -232,6 +232,10 @@ static int dgram_sendmsg(struct kiocb *iocb, struct sock *sk,
 
 	hlen = LL_RESERVED_SPACE(dev);
 	tlen = dev->needed_tailroom;
+	if (hlen + tlen + size > USHRT_MAX) {
+		err = -EMSGSIZE;
+		goto out;
+	}
 	skb = sock_alloc_send_skb(sk, hlen + tlen + size,
 			msg->msg_flags & MSG_DONTWAIT,
 			&err);
-- 
1.7.8.6


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