From: Stefan Hajnoczi Date: Wed, 27 Mar 2013 09:10:46 +0000 (+0100) Subject: chardev: clear O_NONBLOCK on SCM_RIGHTS file descriptors X-Git-Tag: qemu-xen-4.4.0-rc1~6^2~788^2 X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=9b938c7262e403f5467110609cb20ef1ae6e9df2;p=qemu-upstream-4.4-testing.git 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: Stefan Hajnoczi Reviewed-by: Eric Blake Signed-off-by: Luiz Capitulino --- diff --git a/qemu-char.c b/qemu-char.c index 4d8c6cab4..d825b6017 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -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