Commit 9b938c72 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi Committed by Luiz Capitulino
Browse files

chardev: clear O_NONBLOCK on SCM_RIGHTS file descriptors 



When we receive a file descriptor over a UNIX domain socket the
O_NONBLOCK flag is preserved.  Clear the O_NONBLOCK flag and rely on
QEMU file descriptor users like migration, SPICE, VNC, block layer, and
others to set non-blocking only when necessary.

This change ensures we don't accidentally expose O_NONBLOCK in the QMP
API.  QMP clients should not need to get the non-blocking state
"correct".

A recent real-world example was when libvirt passed a non-blocking TCP
socket for migration where we expected a blocking socket.  The source
QEMU produced a corrupted migration stream since its code did not cope
with non-blocking sockets.

Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarLuiz Capitulino <lcapitulino@redhat.com>
parent 1a751ebf

qemu-char.c

+3 −0
Original line number Diff line number Diff line
@@ -2440,6 +2440,9 @@ static void unix_process_msgfd(CharDriverState *chr, struct msghdr *msg) 
        if (fd < 0)

            continue;



        /* O_NONBLOCK is preserved across SCM_RIGHTS so reset it */

        qemu_set_block(fd);



#ifndef MSG_CMSG_CLOEXEC

        qemu_set_cloexec(fd);

#endif