* [Qemu-devel] [PATCH v2] sockets: avoid leak of listen file descriptor
@ 2017-10-20 14:12 Daniel P. Berrange
2017-10-20 20:14 ` Eric Blake
0 siblings, 1 reply; 2+ messages in thread
From: Daniel P. Berrange @ 2017-10-20 14:12 UTC (permalink / raw)
To: qemu-devel; +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 <berrange@redhat.com>
---
util/qemu-sockets.c | 52 +++++++++++++++++++++++++++++-----------------------
1 file changed, 29 insertions(+), 23 deletions(-)
diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index b47fb45885..4587829552 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 succeeed 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,
--
2.13.6
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [PATCH v2] sockets: avoid leak of listen file descriptor
2017-10-20 14:12 [Qemu-devel] [PATCH v2] sockets: avoid leak of listen file descriptor Daniel P. Berrange
@ 2017-10-20 20:14 ` Eric Blake
0 siblings, 0 replies; 2+ messages in thread
From: Eric Blake @ 2017-10-20 20:14 UTC (permalink / raw)
To: Daniel P. Berrange, qemu-devel; +Cc: Paolo Bonzini
[-- Attachment #1: Type: text/plain, Size: 1195 bytes --]
On 10/20/2017 09:12 AM, Daniel P. Berrange wrote:
> 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 <berrange@redhat.com>
> ---
> util/qemu-sockets.c | 52 +++++++++++++++++++++++++++++-----------------------
> 1 file changed, 29 insertions(+), 23 deletions(-)
>
> + 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
s/succeeed/succeed/
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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