From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36632) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZHtkJ-00045d-CR for qemu-devel@nongnu.org; Wed, 22 Jul 2015 09:07:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZHtkI-0007SR-GL for qemu-devel@nongnu.org; Wed, 22 Jul 2015 09:07:39 -0400 From: "Richard W.M. Jones" Date: Wed, 22 Jul 2015 14:07:22 +0100 Message-Id: <1437570442-30203-2-git-send-email-rjones@redhat.com> In-Reply-To: <1437570442-30203-1-git-send-email-rjones@redhat.com> References: <1437570442-30203-1-git-send-email-rjones@redhat.com> Subject: [Qemu-devel] [PATCH v2] block/ssh: Avoid segfault if inet_connect doesn't set errno. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, jcody@redhat.com, qemu-block@nongnu.org On some (but not all) systems: $ qemu-img create -f qcow2 overlay -b ssh://xen/ Segmentation fault It turns out this happens when inet_connect returns -1 in the following code, but errno == 0. s->sock = inet_connect(s->hostport, errp); if (s->sock < 0) { ret = -errno; goto err; } In the test case above, no host called "xen" exists, so getaddrinfo fails. On Fedora 22, getaddrinfo happens to set errno = ENOENT (although it is *not* documented to do that), so it doesn't segfault. On RHEL 7, errno is not set by the failing getaddrinfo, so ret = -errno = 0, so the caller doesn't know there was an error and continues with a half-initialized BDRVSSHState struct, and everything goes south from there, eventually resulting in a segfault. Fix this by setting ret to -EINVAL. The real error is saved in the Error** errp struct, so it is printed correctly: $ ./qemu-img create -f qcow2 overlay -b ssh://xen/ qemu-img: overlay: address resolution failed for xen:22: No address associated with hostname Signed-off-by: Richard W.M. Jones Reported-by: Jun Li BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1147343 --- block/ssh.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/ssh.c b/block/ssh.c index aebb18c..8d4dc2a 100644 --- a/block/ssh.c +++ b/block/ssh.c @@ -563,7 +563,7 @@ static int connect_to_ssh(BDRVSSHState *s, QDict *options, /* Open the socket and connect. */ s->sock = inet_connect(s->hostport, errp); if (s->sock < 0) { - ret = -errno; + ret = -EINVAL; goto err; } -- 2.4.3