mm/gup: fix memory leak in __gup_benchmark_ioctl

In the implementation of __gup_benchmark_ioctl() the allocated pages
should be released before returning in case of an invalid cmd.  Release
pages via kvfree().

[akpm@linux-foundation.org: rework code flow, return -EINVAL rather than -1]
Link: http://lkml.kernel.org/r/20191211174653.4102-1-navid.emamdoost@gmail.com
Fixes: 714a3a1 ("mm/gup_benchmark.c: add additional pinning methods")
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Navidem

mm/gup_benchmark.c

@@ -26,6 +26,7 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
 	unsigned long i, nr_pages, addr, next;
 	int nr;
 	struct page **pages;
+	int ret = 0;
 
 	if (gup->size > ULONG_MAX)
 		return -EINVAL;
@@ -63,7 +64,9 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
 					    NULL);
 			break;
 		default:
-			return -1;
+			kvfree(pages);
+			ret = -EINVAL;
+			goto out;
 		}
 
 		if (nr <= 0)
@@ -85,7 +88,8 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
 	gup->put_delta_usec = ktime_us_delta(end_time, start_time);
 
 	kvfree(pages);
-	return 0;
+out:
+	return ret;
 }
 
 static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,