In the zerocopy sendmsg() path, there are error checks to revert
the zerocopy if we get any error code.  syzkaller has discovered
that tls_push_record can return -ECONNRESET, which is fatal, and
happens after the point at which it is safe to revert the iter,
as we've already passed the memory to do_tcp_sendpages.

Previously this code could return -ENOMEM and we would want to
revert the iter, but AFAIK this no longer returns ENOMEM after
a447da7d ("tls: fix waitall behavior in tls_sw_recvmsg"),
so we fail for all error codes.

Reported-by: syzbot+c226690f7b3126c5ee04@syzkaller.appspotmail.com
Reported-by: syzbot+709f2810a6a05f11d4d3@syzkaller.appspotmail.com
Signed-off-by: NDave Watson <davejwatson@fb.com>
Fixes: 3c4d7559 ("tls: kernel TLS support")
Signed-off-by: NDavid S. Miller <davem@davemloft.net>