avoid accessing mutex memory after atomic unlock

[musl] / src / thread / pthread_mutex_timedlock.c

diff --git a/src/thread/pthread_mutex_timedlock.c b/src/thread/pthread_mutex_timedlock.c
index f1c3eed..ae1e2c3 100644 (file)
--- a/src/thread/pthread_mutex_timedlock.c
+++ b/src/thread/pthread_mutex_timedlock.c
@@ -2,15 +2,23 @@
 
 int pthread_mutex_timedlock(pthread_mutex_t *m, const struct timespec *at)
 {
-       int r, w=0;
+       int r, t;
+
+       if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_cas(&m->_m_lock, 0, EBUSY))
+               return 0;
+
        while ((r=pthread_mutex_trylock(m)) == EBUSY) {
                if (!(r=m->_m_lock) || (r&0x40000000)) continue;
-               if (!w) a_inc(&m->_m_waiters), w++;
-               if (__timedwait(&m->_m_lock, r, CLOCK_REALTIME, at, 0) == ETIMEDOUT) {
-                       if (w) a_dec(&m->_m_waiters);
-                       return ETIMEDOUT;
-               }
+               if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK
+                && (r&0x1fffffff) == pthread_self()->tid)
+                       return EDEADLK;
+
+               a_inc(&m->_m_waiters);
+               t = r | 0x80000000;
+               a_cas(&m->_m_lock, r, t);
+               r = __timedwait(&m->_m_lock, t, CLOCK_REALTIME, at, 0);
+               a_dec(&m->_m_waiters);
+               if (r && r != EINTR) break;
        }
-       if (w) a_dec(&m->_m_waiters);
        return r;
 }