Commits
Willem de Bruijn committed 522924b5830
net: correct udp zerocopy refcnt also when zerocopy only on append
The below patch fixes an incorrect zerocopy refcnt increment when
appending with MSG_MORE to an existing zerocopy udp skb.
send(.., MSG_ZEROCOPY | MSG_MORE); // refcnt 1
send(.., MSG_ZEROCOPY | MSG_MORE); // refcnt still 1 (bar frags)
But it missed that zerocopy need not be passed at the first send. The
right test whether the uarg is newly allocated and thus has extra
refcnt 1 is not !skb, but !skb_zcopy.
send(.., MSG_MORE); // <no uarg>
send(.., MSG_ZEROCOPY); // refcnt 1
Fixes: 100f6d8e09905 ("net: correct zerocopy refcnt with udp MSG_MORE")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>