*) SECURITY: CAN-2004-0174 (cve.mitre.org)

     Fix starvation issue on listening sockets where a short-lived
     connection on a rarely-accessed listening socket will cause a
     child to hold the accept mutex and block out new connections until
     another connection arrives on that rarely-accessed listening socket.
     With Apache 2.x there is no performance concern about enabling the
     logic for platforms which don't need it, so it is enabled everywhere
     except for Win32.  [Jeff Trawick]

(already in 2.0.49, propagating to mirrors now)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@103029 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 20 insertions, 3 deletions

diff --git a/server/listen.c b/server/listen.c
index 56a99751bc..e6873baec4 100644
--- a/server/listen.c
+++ b/server/listen.c
@@ -383,6 +383,26 @@ static int ap_listen_open(apr_pool_t *pool, apr_port_t port)
     }
     old_listeners = NULL;
 
+#if AP_NONBLOCK_WHEN_MULTI_LISTEN
+    /* if multiple listening sockets, make them non-blocking so that
+     * if select()/poll() reports readability for a reset connection that
+     * is already forgotten about by the time we call accept, we won't
+     * be hung until another connection arrives on that port
+     */
+    if (ap_listeners->next) {
+        for (lr = ap_listeners; lr; lr = lr->next) {
+            apr_status_t status;
+
+            status = apr_socket_opt_set(lr->sd, APR_SO_NONBLOCK, 1);
+            if (status != APR_SUCCESS) {
+                ap_log_perror(APLOG_MARK, APLOG_STARTUP|APLOG_ERR, status, pool,
+                              "ap_listen_open: unable to make socket non-blocking");
+                return -1;
+            }
+        }
+    }
+#endif /* AP_NONBLOCK_WHEN_MULTI_LISTEN */
+
     /* we come through here on both passes of the open logs phase
      * only register the cleanup once... otherwise we try to close
      * listening sockets twice when cleaning up prior to exec
diff --git a/server/mpm/netware/mpm_netware.c b/server/mpm/netware/mpm_netware.c
index 34e8cbf56e..27f0e51720 100644
--- a/server/mpm/netware/mpm_netware.c
+++ b/server/mpm/netware/mpm_netware.c
@@ -828,9 +828,6 @@ static int setup_listeners(server_rec *s)
         if (sockdes > listenmaxfd) {
             listenmaxfd = sockdes;
         }
-        /* Use non-blocking listen sockets so that we
-           never get hung up. */
-        apr_socket_opt_set(lr->sd, APR_SO_NONBLOCK, 1);
     }
     return 0;
 }