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tcp-zerocopy: Update returned getsockopt() optlen.

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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>
This commit is contained in:
Arjun Roy 2020-02-25 12:38:54 -08:00 committed by David S. Miller
parent ebb4a4bf76
commit 0b7f41f687
1 changed files with 4 additions and 1 deletions
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5
net/ipv4/tcp.c
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@ -3669,8 +3669,11 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
return -EFAULT; return -EFAULT;
if (len < offsetofend(struct tcp_zerocopy_receive, length)) if (len < offsetofend(struct tcp_zerocopy_receive, length))
return -EINVAL; return -EINVAL;
if (len > sizeof(zc)) if (len > sizeof(zc)) {
len = sizeof(zc); len = sizeof(zc);
if (put_user(len, optlen))
return -EFAULT;
}
if (copy_from_user(&zc, optval, len)) if (copy_from_user(&zc, optval, len))
return -EFAULT; return -EFAULT;
lock_sock(sk); lock_sock(sk);