apr_os_proc_mutex_get() segfault

[Yann Ylavic]

Hi,

when using the following code :

    pthread_mutex_t *mymutex;
    apr_proc_mutex_t *apmutex = NULL;
    apr_os_proc_mutex_t osmutex = {0};
    apr_proc_mutex_create(&apmutex, NULL, APR_LOCK_PROC_PTHREAD, p);
    apr_os_proc_mutex_get(&osmutex, apmutex);
    mymutex = osmutex.pthread_interproc;

apr_os_proc_mutex_get() derefences the NULL pointer.

The function is implemented like this :

APR_DECLARE(apr_status_t) apr_os_proc_mutex_get(apr_os_proc_mutex_t *ospmutex,
                                                apr_proc_mutex_t *pmutex)
{
#if APR_HAS_SYSVSEM_SERIALIZE || APR_HAS_FCNTL_SERIALIZE ||
APR_HAS_FLOCK_SERIALIZE || APR_HAS_POSIXSEM_SERIALIZE
    ospmutex->crossproc = pmutex->interproc->filedes;
#endif
#if APR_HAS_PROC_PTHREAD_SERIALIZE
    ospmutex->pthread_interproc = pmutex->pthread_interproc;
#endif
    return APR_SUCCESS;
}

The problem is that on my linux system, all these APR_HAS_*_SERIALIZE
are defined to 1, but when a APR_LOCK_PROC_PTHREAD mutex is created,
apr_proc_mutex_t->pthread_interproc only is initialized, and
apr_proc_mutex_t->interproc is NULL (hence the segfault).

Maybe the patch above could be applied :

Index: locks/unix/proc_mutex.c
===================================================================
--- locks/unix/proc_mutex.c    (revision 1582271)
+++ locks/unix/proc_mutex.c    (working copy)
@@ -1013,7 +1013,12 @@ APR_DECLARE(apr_status_t) apr_os_proc_mutex_get(ap
                                                 apr_proc_mutex_t *pmutex)
 {
 #if APR_HAS_SYSVSEM_SERIALIZE || APR_HAS_FCNTL_SERIALIZE ||
APR_HAS_FLOCK_SERIALIZE || APR_HAS_POSIXSEM_SERIALIZE
-    ospmutex->crossproc = pmutex->interproc->filedes;
+    if (pmutex->interproc) {
+        ospmutex->crossproc = pmutex->interproc->filedes;
+    }
+    else {
+        ospmutex->crossproc = -1;
+    }
 #endif
 #if APR_HAS_PROC_PTHREAD_SERIALIZE
     ospmutex->pthread_interproc = pmutex->pthread_interproc;
[END]

Regards,
Yann.