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authorVincent Whitchurch <vincent.whitchurch@axis.com>2018-09-06 15:54:59 +0200
committerDavid S. Miller <davem@davemloft.net>2018-09-07 23:11:06 -0700
commit5cf4a8532c992bb22a9ecd5f6d93f873f4eaccc2 (patch)
treec3a217b0a679c4821e045f32ddfff995b0dc5b9d /net/ipv4
parenta162c3511410b50f09c002fea56fea2153b679d0 (diff)
tcp: really ignore MSG_ZEROCOPY if no SO_ZEROCOPY
According to the documentation in msg_zerocopy.rst, the SO_ZEROCOPY flag was introduced because send(2) ignores unknown message flags and any legacy application which was accidentally passing the equivalent of MSG_ZEROCOPY earlier should not see any new behaviour. Before commit f214f915e7db ("tcp: enable MSG_ZEROCOPY"), a send(2) call which passed the equivalent of MSG_ZEROCOPY without setting SO_ZEROCOPY would succeed. However, after that commit, it fails with -ENOBUFS. So it appears that the SO_ZEROCOPY flag fails to fulfill its intended purpose. Fix it. Fixes: f214f915e7db ("tcp: enable MSG_ZEROCOPY") Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index b8af2fec5ad5..10c6246396cc 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1185,7 +1185,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
flags = msg->msg_flags;
- if (flags & MSG_ZEROCOPY && size) {
+ if (flags & MSG_ZEROCOPY && size && sock_flag(sk, SOCK_ZEROCOPY)) {
if (sk->sk_state != TCP_ESTABLISHED) {
err = -EINVAL;
goto out_err;