From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56227) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e5Tbo-00080n-Jx for qemu-devel@nongnu.org; Fri, 20 Oct 2017 05:28:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e5Tbl-0000Ft-BY for qemu-devel@nongnu.org; Fri, 20 Oct 2017 05:28:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56384) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1e5Tbl-0000F0-3I for qemu-devel@nongnu.org; Fri, 20 Oct 2017 05:28:49 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 22CCD4792 for ; Fri, 20 Oct 2017 09:28:48 +0000 (UTC) From: "Daniel P. Berrange" Date: Fri, 20 Oct 2017 10:28:44 +0100 Message-Id: <20171020092844.13880-1-berrange@redhat.com> Subject: [Qemu-devel] [PATCH] sockets: avoid leak of listen file descriptor List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Eric Blake , "Daniel P. Berrange" If we iterate over the full port range without successfully binding+listening on the socket, we'll try the next address, whereupon we overwrite the slisten file descriptor variable without closing it. Rather than having two places where we open + close socket FDs on different iterations of nested for loops, re-arrange the code to always open+close within the same loop iteration. Signed-off-by: Daniel P. Berrange --- util/qemu-sockets.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c index b47fb45885..a319338cca 100644 --- a/util/qemu-sockets.c +++ b/util/qemu-sockets.c @@ -207,7 +207,7 @@ static int inet_listen_saddr(InetSocketAddress *saddr, char uaddr[INET6_ADDRSTRLEN+1]; char uport[33]; int rc, port_min, port_max, p; - int slisten = 0; + int slisten = -1; int saved_errno = 0; bool socket_created = false; Error *err = NULL; @@ -267,16 +267,28 @@ static int inet_listen_saddr(InetSocketAddress *saddr, uaddr,INET6_ADDRSTRLEN,uport,32, NI_NUMERICHOST | NI_NUMERICSERV); - slisten = create_fast_reuse_socket(e); - if (slisten < 0) { - continue; - } - socket_created = true; port_min = inet_getport(e); port_max = saddr->has_to ? saddr->to + port_offset : port_min; for (p = port_min; p <= port_max; p++) { inet_setport(e, p); + + slisten = create_fast_reuse_socket(e); + if (slisten < 0) { + /* First time we expect we might fail to create the socket + * eg if 'e' has AF_INET6 but ipv6 kmod is not loaded. + * Later iterations should always succeeed if first iteration + * worked though, so treat that as fatal. + */ + if (p == port_min) { + continue; + } else { + error_setg_errno(errp, errno, + "Failed to recreate failed listening socket"); + goto listen_failed; + } + } + rc = try_bind(slisten, saddr, e); if (rc) { if (errno == EADDRINUSE) { @@ -299,12 +311,7 @@ static int inet_listen_saddr(InetSocketAddress *saddr, * socket to allow bind attempts for subsequent ports: */ closesocket(slisten); - slisten = create_fast_reuse_socket(e); - if (slisten < 0) { - error_setg_errno(errp, errno, - "Failed to recreate failed listening socket"); - goto listen_failed; - } + slisten = -1; } } error_setg_errno(errp, errno, -- 2.13.6