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: c8856c051454 ("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>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1b68548..48aa457 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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);