SECURITY (CVE-2014-0226): Fix a race condition in scoreboard handling,

which could lead to a heap buffer overflow.  Thanks to Marek Kroemeke
working with HP's Zero Day Initiative for reporting this.

* include/scoreboard.h: Add ap_copy_scoreboard_worker.

* server/scoreboard.c (ap_copy_scoreboard_worker): New function.

* modules/generators/mod_status.c (status_handler): Use it.

* modules/lua/lua_request.c (lua_ap_scoreboard_worker): Likewise.

Reviewed by: trawick, jorton, covener, jim
Submitted by: jorton, covener


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1610491 13f79535-47bb-0310-9956-ffa450edef68

5 files changed, 47 insertions, 8 deletions

diff --git a/include/ap_mmn.h b/include/ap_mmn.h
index 0f5485f315..4c82c364dc 100644
--- a/include/ap_mmn.h
+++ b/include/ap_mmn.h
@@ -466,6 +466,7 @@
  * 20140627.1 (2.5.0-dev)  add last_backend_conn to util_ldap_connection_t
  * 20140627.2 (2.5.0-dev)  Added is_name_matchable to proxy_worker_shared.
                            Added ap_proxy_define_match_worker().
+ * 20140627.3 (2.5.0-dev)  Add ap_copy_scoreboard_worker()
  */
 
 #define MODULE_MAGIC_COOKIE 0x41503235UL /* "AP25" */
@@ -473,7 +474,7 @@
 #ifndef MODULE_MAGIC_NUMBER_MAJOR
 #define MODULE_MAGIC_NUMBER_MAJOR 20140627
 #endif
-#define MODULE_MAGIC_NUMBER_MINOR 2                 /* 0...n */
+#define MODULE_MAGIC_NUMBER_MINOR 3                 /* 0...n */
 
 /**
  * Determine if the server's current MODULE_MAGIC_NUMBER is at least a
diff --git a/include/scoreboard.h b/include/scoreboard.h
index d2be9c87a7..c41d7d3f0b 100644
--- a/include/scoreboard.h
+++ b/include/scoreboard.h
@@ -183,8 +183,25 @@ AP_DECLARE(int) ap_update_child_status_from_conn(ap_sb_handle_t *sbh, int status
 AP_DECLARE(void) ap_time_process_request(ap_sb_handle_t *sbh, int status);
 
 AP_DECLARE(worker_score *) ap_get_scoreboard_worker(ap_sb_handle_t *sbh);
+
+/** Return a pointer to the worker_score for a given child, thread pair.
+ * @param child_num The child number.
+ * @param thread_num The thread number.
+ * @return A pointer to the worker_score structure.
+ * @deprecated This function is deprecated, use ap_copy_scoreboard_worker instead. */
 AP_DECLARE(worker_score *) ap_get_scoreboard_worker_from_indexes(int child_num,
                                                                 int thread_num);
+
+/** Copy the contents of a worker scoreboard entry.  The contents of
+ * the worker_score structure are copied verbatim into the dest
+ * structure, which must have sizeof(worker_score).
+ * @param dest Output parameter.
+ * @param child_num The child number.
+ * @param thread_num The thread number.
+ */
+AP_DECLARE(void) ap_copy_scoreboard_worker(worker_score *dest,
+                                           int child_num, int thread_num);
+
 AP_DECLARE(process_score *) ap_get_scoreboard_process(int x);
 AP_DECLARE(global_score *) ap_get_scoreboard_global(void);
 
diff --git a/modules/generators/mod_status.c b/modules/generators/mod_status.c
index fe832b32d0..6bcf592b57 100644
--- a/modules/generators/mod_status.c
+++ b/modules/generators/mod_status.c
@@ -194,7 +194,7 @@ static int status_handler(request_rec *r)
     long req_time;
     int short_report;
     int no_table_report;
-    worker_score *ws_record;
+    worker_score *ws_record = apr_palloc(r->pool, sizeof *ws_record);
     process_score *ps_record;
     char *stat_buffer;
     pid_t *pid_buffer, worker_pid;
@@ -306,7 +306,7 @@ static int status_handler(request_rec *r)
         for (j = 0; j < thread_limit; ++j) {
             int indx = (i * thread_limit) + j;
 
-            ws_record = ap_get_scoreboard_worker_from_indexes(i, j);
+            ap_copy_scoreboard_worker(ws_record, i, j);
             res = ws_record->status;
 
             if ((i >= max_servers || j >= threads_per_child)
@@ -637,7 +637,7 @@ static int status_handler(request_rec *r)
 
         for (i = 0; i < server_limit; ++i) {
             for (j = 0; j < thread_limit; ++j) {
-                ws_record = ap_get_scoreboard_worker_from_indexes(i, j);
+                ap_copy_scoreboard_worker(ws_record, i, j);
 
                 if (ws_record->access_count == 0 &&
                     (ws_record->status == SERVER_READY ||
diff --git a/modules/lua/lua_request.c b/modules/lua/lua_request.c
index 445e3caf1f..1e97fb5438 100644
--- a/modules/lua/lua_request.c
+++ b/modules/lua/lua_request.c
@@ -1242,16 +1242,22 @@ static int lua_ap_scoreboard_process(lua_State *L)
  */
 static int lua_ap_scoreboard_worker(lua_State *L)
 {
-    int i,
-        j;
-    worker_score   *ws_record;
+    int i, j;
+    worker_score *ws_record = NULL;
+    request_rec *r = NULL;
 
     luaL_checktype(L, 1, LUA_TUSERDATA);
     luaL_checktype(L, 2, LUA_TNUMBER);
     luaL_checktype(L, 3, LUA_TNUMBER);
+
+    r = ap_lua_check_request_rec(L, 1);
+    if (!r) return 0;
+
     i = lua_tointeger(L, 2);
     j = lua_tointeger(L, 3);
-    ws_record = ap_get_scoreboard_worker_from_indexes(i, j);
+    ws_record = apr_palloc(r->pool, sizeof *ws_record);
+
+    ap_copy_scoreboard_worker(ws_record, i, j);
     if (ws_record) {
         lua_newtable(L);
 
diff --git a/server/scoreboard.c b/server/scoreboard.c
index ba0ef6a3ee..befb2bcdc2 100644
--- a/server/scoreboard.c
+++ b/server/scoreboard.c
@@ -579,6 +579,21 @@ AP_DECLARE(worker_score *) ap_get_scoreboard_worker(ap_sb_handle_t *sbh)
                                                  sbh->thread_num);
 }
 
+AP_DECLARE(void) ap_copy_scoreboard_worker(worker_score *dest, 
+                                           int child_num,
+                                           int thread_num)
+{
+    worker_score *ws = ap_get_scoreboard_worker_from_indexes(child_num, thread_num);
+
+    memcpy(dest, ws, sizeof *ws);
+
+    /* For extra safety, NUL-terminate the strings returned, though it
+     * should be true those last bytes are always zero anyway. */
+    dest->client[sizeof(dest->client) - 1] = '\0';
+    dest->request[sizeof(dest->request) - 1] = '\0';
+    dest->vhost[sizeof(dest->vhost) - 1] = '\0';
+}
+
 AP_DECLARE(process_score *) ap_get_scoreboard_process(int x)
 {
     if ((x < 0) || (x >= server_limit)) {