From 10a7b7e6fd9f250f0506568345d7b4d2ab52889d Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" Date: Fri, 20 Oct 2017 10:18:39 +0100 Subject: sockets: avoid leak of listen file descriptor 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. Reviewed-by: Eric Blake Signed-off-by: Daniel P. Berrange --- util/qemu-sockets.c | 52 +++++++++++++++++++++++++++++----------------------- 1 file changed, 29 insertions(+), 23 deletions(-) (limited to 'util/qemu-sockets.c') diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c index b47fb45885..8b75541ce4 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; @@ -267,31 +267,42 @@ 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); - rc = try_bind(slisten, saddr, e); - if (rc) { - if (errno == EADDRINUSE) { + + 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 succeed if first iteration + * worked though, so treat that as fatal. + */ + if (p == port_min) { continue; } else { - error_setg_errno(errp, errno, "Failed to bind socket"); + error_setg_errno(errp, errno, + "Failed to recreate failed listening socket"); goto listen_failed; } } - if (!listen(slisten, 1)) { - goto listen_ok; - } - if (errno != EADDRINUSE) { - error_setg_errno(errp, errno, "Failed to listen on socket"); - goto listen_failed; + socket_created = true; + + rc = try_bind(slisten, saddr, e); + if (rc < 0) { + if (errno != EADDRINUSE) { + error_setg_errno(errp, errno, "Failed to bind socket"); + goto listen_failed; + } + } else { + if (!listen(slisten, 1)) { + goto listen_ok; + } + if (errno != EADDRINUSE) { + error_setg_errno(errp, errno, "Failed to listen on socket"); + goto listen_failed; + } } /* Someone else managed to bind to the same port and beat us * to listen on it! Socket semantics does not allow us to @@ -299,12 +310,7 @@ 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, -- cgit v1.2.3