Commit 0b7f41f6 authored Feb 25, 2020 by Arjun Roy Committed by David S. Miller Feb 26, 2020

tcp-zerocopy: Update returned getsockopt() optlen.

TCP receive zerocopy currently does not update the returned optlen for
getsockopt() if the user passed in a larger than expected value.
Thus, userspace cannot properly determine if all the fields are set in
the passed-in struct. This patch sets the optlen for this case before
returning, in keeping with the expected operation of getsockopt().

Fixes: c8856c05 ("tcp-zerocopy: Return inq along with tcp receive zerocopy.")
Signed-off-by: Arjun Roy <arjunroy@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ebb4a4bf

net/ipv4/tcp.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -3669,8 +3669,11 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
		return -EFAULT;
		if (len < offsetofend(struct tcp_zerocopy_receive, length))
		return -EINVAL;
		if (len > sizeof(zc))
		if (len > sizeof(zc)) {
		len = sizeof(zc);
		if (put_user(len, optlen))
		return -EFAULT;
		}
		if (copy_from_user(&zc, optval, len))
		return -EFAULT;
		lock_sock(sk);