From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:54996) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UKmQ4-0002nm-JT for qemu-devel@nongnu.org; Wed, 27 Mar 2013 05:13:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UKmNo-0001VO-R1 for qemu-devel@nongnu.org; Wed, 27 Mar 2013 05:11:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:64919) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UKmNo-0001VH-Gi for qemu-devel@nongnu.org; Wed, 27 Mar 2013 05:11:00 -0400 From: Stefan Hajnoczi Date: Wed, 27 Mar 2013 10:10:46 +0100 Message-Id: <1364375446-24180-5-git-send-email-stefanha@redhat.com> In-Reply-To: <1364375446-24180-1-git-send-email-stefanha@redhat.com> References: <1364375446-24180-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH v2 4/4] chardev: clear O_NONBLOCK on SCM_RIGHTS file descriptors List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Anthony Liguori , Juan Quintela , mprivozn@redhat.com, coreyb@linux.vnet.ibm.com, david.pravec@nethost.cz, Luiz Capitulino , Stefan Hajnoczi 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 --- qemu-char.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/qemu-char.c b/qemu-char.c index 500a582..091f2dc 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -2434,6 +2434,9 @@ 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 -- 1.8.1.4