From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36520) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y2tz5-0005XZ-52 for qemu-devel@nongnu.org; Sun, 21 Dec 2014 22:48:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y2tyy-00084l-VP for qemu-devel@nongnu.org; Sun, 21 Dec 2014 22:48:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38027) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y2tyy-00083W-OQ for qemu-devel@nongnu.org; Sun, 21 Dec 2014 22:48:32 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sBM3mUtY012893 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Sun, 21 Dec 2014 22:48:30 -0500 Message-ID: <5497948D.5050900@redhat.com> Date: Mon, 22 Dec 2014 11:48:29 +0800 From: Jason Wang MIME-Version: 1.0 References: <1418995502-14908-1-git-send-email-akong@redhat.com> In-Reply-To: <1418995502-14908-1-git-send-email-akong@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] check return value of fcntl() to detect invalid fd List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Amos Kong , qemu-devel@nongnu.org Cc: stefanha@redhat.com, mst@redhat.com On 12/19/2014 09:25 PM, Amos Kong wrote: > Passing some invalid fds in QEMU commandline, the fds don't exist. > QEMU will get error "TUNGETIFF ioctl() failed: Bad file descriptor", > and coredump in setting queues. > > This patch checked return value of first operate to fd, QEMU will > report error and exit without coredump. It's effected for both netdev > fds and vhost_net fds. > > Signed-off-by: Amos Kong > --- > net/tap.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/net/tap.c b/net/tap.c > index bde6b58..039280a 100644 > --- a/net/tap.c > +++ b/net/tap.c > @@ -688,7 +688,7 @@ int net_init_tap(const NetClientOptions *opts, const char *name, > NetClientState *peer) > { > const NetdevTapOptions *tap; > - int fd, vnet_hdr = 0, i = 0, queues; > + int fd, vnet_hdr = 0, i = 0, queues, ret; > /* for the no-fd, no-helper case */ > const char *script = NULL; /* suppress wrong "uninit'd use" gcc warning */ > const char *downscript = NULL; > @@ -722,7 +722,12 @@ int net_init_tap(const NetClientOptions *opts, const char *name, > return -1; > } > > - fcntl(fd, F_SETFL, O_NONBLOCK); > + ret = fcntl(fd, F_SETFL, O_NONBLOCK); > + if (ret < 0) { > + error_report("Fail to set file status to nonblock, " > + "%s", strerror(-ret)); > + return -1; > + } This may not work. There may be still some kinds of fd can pass this but still fail at TUNGETIFF or other tun ioctls. Probably you need to fail during TUNGETIFF, which can make sure it was not a tap fd. > > vnet_hdr = tap_probe_vnet_hdr(fd); > > @@ -761,7 +766,12 @@ int net_init_tap(const NetClientOptions *opts, const char *name, > return -1; > } > > - fcntl(fd, F_SETFL, O_NONBLOCK); > + ret = fcntl(fd, F_SETFL, O_NONBLOCK); > + if (ret < 0) { > + error_report("Fail to set file status to nonblock, " > + "%s", strerror(-ret)); > + return -1; > + } > > if (i == 0) { > vnet_hdr = tap_probe_vnet_hdr(fd);