[Xen-devel] [PATCH] Fix libxenstore memory leak when USE_PTHREAD is not defined

[Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>]

 tools/xenstore/xs.c |  22 ++++++----------------
 1 files changed, 6 insertions(+), 16 deletions(-)


Remove usage of pthread_cleanup_push and _pop, and explicitly call free for
heap objects in error paths. Also remove cleanup_p* for a mutex unlock path. By
the way, set a suitable errno value for an error path that had none.

Resend due to small fix spotted, please ignore previous one.

Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>

diff -r 588d0dc298a4 -r 9bfaf86e061f tools/xenstore/xs.c
--- a/tools/xenstore/xs.c
+++ b/tools/xenstore/xs.c
@@ -99,14 +99,6 @@ struct xs_handle {
 #define mutex_unlock(m)                pthread_mutex_unlock(m)
 #define condvar_signal(c)      pthread_cond_signal(c)
 #define condvar_wait(c,m)      pthread_cond_wait(c,m)
-#define cleanup_push(f, a)     \
-    pthread_cleanup_push((void (*)(void *))(f), (void *)(a))
-/*
- * Some definitions of pthread_cleanup_pop() are a macro starting with an
- * end-brace. GCC then complains if we immediately precede that with a label.
- * Hence we insert a dummy statement to appease the compiler in this situation.
- */
-#define cleanup_pop(run)        ((void)0); pthread_cleanup_pop(run)
 
 #define read_thread_exists(h)  (h->read_thr_exists)
 
@@ -126,8 +118,6 @@ struct xs_handle {
 #define mutex_unlock(m)                ((void)0)
 #define condvar_signal(c)      ((void)0)
 #define condvar_wait(c,m)      ((void)0)
-#define cleanup_push(f, a)     ((void)0)
-#define cleanup_pop(run)       ((void)0)
 #define read_thread_exists(h)  (0)
 
 #endif
@@ -1059,7 +1049,6 @@ static int read_message(struct xs_handle
        msg = malloc(sizeof(*msg));
        if (msg == NULL)
                goto error;
-       cleanup_push(free, msg);
        if (!read_all(h->fd, &msg->hdr, sizeof(msg->hdr), nonblocking)) { /* 
Cancellation point */
                saved_errno = errno;
                goto error_freemsg;
@@ -1069,7 +1058,6 @@ static int read_message(struct xs_handle
        body = msg->body = malloc(msg->hdr.len + 1);
        if (body == NULL)
                goto error_freemsg;
-       cleanup_push(free, body);
        if (!read_all(h->fd, body, msg->hdr.len, 0)) { /* Cancellation point */
                saved_errno = errno;
                goto error_freebody;
@@ -1079,7 +1067,6 @@ static int read_message(struct xs_handle
 
        if (msg->hdr.type == XS_WATCH_EVENT) {
                mutex_lock(&h->watch_mutex);
-               cleanup_push(pthread_mutex_unlock, &h->watch_mutex);
 
                /* Kick users out of their select() loop. */
                if (list_empty(&h->watch_list) &&
@@ -1091,13 +1078,14 @@ static int read_message(struct xs_handle
 
                condvar_signal(&h->watch_condvar);
 
-               cleanup_pop(1);
+               mutex_unlock(&h->watch_mutex);
        } else {
                mutex_lock(&h->reply_mutex);
 
                /* There should only ever be one response pending! */
                if (!list_empty(&h->reply_list)) {
                        mutex_unlock(&h->reply_mutex);
+                       saved_errno = EEXIST; 
                        goto error_freebody;
                }
 
@@ -1110,9 +1098,11 @@ static int read_message(struct xs_handle
        ret = 0;
 
 error_freebody:
-       cleanup_pop(ret == -1);
+       if (ret)
+               free(body);
 error_freemsg:
-       cleanup_pop(ret == -1);
+       if (ret)
+               free(msg);
 error:
        errno = saved_errno;
 

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