--- subversion-1.14.1/subversion/libsvn_repos/authz.c +++ subversion-1.14.1/subversion/libsvn_repos/authz.c @@ -130,6 +130,30 @@ static svn_object_pool__t *filtered_pool = NULL; static svn_atomic_t authz_pool_initialized = FALSE; +/* + * Ensure that we will initialize authz again if the pool which + * our authz caches depend on is cleared. + * + * HTTPD may run pre/post config hooks multiple times and clear + * its global configuration pool which our authz pools depend on. + * This happens in a non-threaded context during HTTPD's intialization + * and HTTPD's main loop, so it is safe to reset static variables here. + * (And any applications which cleared this pool while SVN threads + * were running would crash no matter what.) + * + * See issue #4880, "Use-after-free of object-pools in + * subversion/libsvn_repos/authz.c when used as httpd module" + */ +static apr_status_t +deinit_authz(void *data) +{ + /* The two object pools run their own cleanup handlers. */ + authz_pool = NULL; + filtered_pool = NULL; + authz_pool_initialized = FALSE; + return APR_SUCCESS; +} + /* Implements svn_atomic__err_init_func_t. */ static svn_error_t * synchronized_authz_initialize(void *baton, apr_pool_t *pool) @@ -143,6 +167,7 @@ SVN_ERR(svn_object_pool__create(&authz_pool, multi_threaded, pool)); SVN_ERR(svn_object_pool__create(&filtered_pool, multi_threaded, pool)); + apr_pool_cleanup_register(pool, NULL, deinit_authz, apr_pool_cleanup_null); return SVN_NO_ERROR; }