ida: Free allocated bitmap in error path

If a bitmap needs to be allocated, and then by the time the thread
is scheduled to be run again all the indices which would satisfy the
allocation have been allocated then we would leak the allocation.  Almost
impossible to hit in practice, but a trivial fix.  Found by Coverity.

Fixes: f32f004cddf8 ("ida: Convert to XArray")
Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

2 files changed, 30 insertions, 0 deletions

diff --git a/lib/idr.c b/lib/idr.c
index c2cf2c52bbde..4d2eef0259d2 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -470,6 +470,7 @@ alloc:
 	goto retry;
 nospc:
 	xas_unlock_irqrestore(&xas, flags);
+	kfree(alloc);
 	return -ENOSPC;
 }
 EXPORT_SYMBOL(ida_alloc_range);
diff --git a/tools/testing/radix-tree/idr-test.c b/tools/testing/radix-tree/idr-test.c
index 8995092d541e..3b796dd5e577 100644
--- a/tools/testing/radix-tree/idr-test.c
+++ b/tools/testing/radix-tree/idr-test.c
@@ -523,8 +523,27 @@ static void *ida_random_fn(void *arg)
 	return NULL;
 }
 
+static void *ida_leak_fn(void *arg)
+{
+	struct ida *ida = arg;
+	time_t s = time(NULL);
+	int i, ret;
+
+	rcu_register_thread();
+
+	do for (i = 0; i < 1000; i++) {
+		ret = ida_alloc_range(ida, 128, 128, GFP_KERNEL);
+		if (ret >= 0)
+			ida_free(ida, 128);
+	} while (time(NULL) < s + 2);
+
+	rcu_unregister_thread();
+	return NULL;
+}
+
 void ida_thread_tests(void)
 {
+	DEFINE_IDA(ida);
 	pthread_t threads[20];
 	int i;
 
@@ -536,6 +555,16 @@ void ida_thread_tests(void)
 
 	while (i--)
 		pthread_join(threads[i], NULL);
+
+	for (i = 0; i < ARRAY_SIZE(threads); i++)
+		if (pthread_create(&threads[i], NULL, ida_leak_fn, &ida)) {
+			perror("creating ida thread");
+			exit(1);
+		}
+
+	while (i--)
+		pthread_join(threads[i], NULL);
+	assert(ida_is_empty(&ida));
 }
 
 void ida_tests(void)