fix mmap leak in sem_open failure path for link call

the leak was found by static analysis (reported by Alexander Monakov),
not tested/observed, but seems to have occured both when failing due
to O_EXCL, and in a race condition with O_CREAT but not O_EXCL where a
semaphore by the same name was created concurrently.

diff --git a/src/thread/sem_open.c b/src/thread/sem_open.c
index ab884a42e00a06ed490a3100eb26562911c80d9d..fda0acd35c717992e44b4c5191e6f400d1190532 100644 (file)
--- a/src/thread/sem_open.c
+++ b/src/thread/sem_open.c
@@ -126,6 +126,7 @@ sem_t *sem_open(const char *name, int flags, ...)
                e = link(tmp, name) ? errno : 0;
                unlink(tmp);
                if (!e) break;
+               munmap(map, sizeof(sem_t));
                /* Failure is only fatal when doing an exclusive open;
                 * otherwise, next iteration will try to open the
                 * existing file. */