[RFC PATCH 09/16] mm: Read the nr_pages_allocs value given by user

[Juan Yescas <jyescas@google.com>]

This change reads the nr_page_allocs value given by the user and
validates that is an unsigned long.

If the input is valid, it will allocate an array of nr_page_allocs
size. This array will store the allocation ids. These allocation ids
will be used to free the allocations.

Signed-off-by: Juan Yescas <jyescas@google.com>
---
 mm/page_alloc_hogger.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/mm/page_alloc_hogger.c b/mm/page_alloc_hogger.c
index 3ffad74a0bdf..60dfddf6b441 100644
--- a/mm/page_alloc_hogger.c
+++ b/mm/page_alloc_hogger.c
@@ -136,6 +136,19 @@ struct kmem_cache *page_alloc_cache;
 static ssize_t req_page_alloc_write(struct file *file, const char __user *ubuf,
 				     size_t cnt, loff_t *ppos)
 {
+	unsigned long nr_pages_allocs;
+	unsigned long *allocs_ids;
+	int ret;
+
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &nr_pages_allocs);
+	if (ret)
+		return ret;
+
+	allocs_ids = kmalloc_array(nr_pages_allocs, sizeof(unsigned long),
+					GFP_KERNEL);
+	if (!allocs_ids)
+		return -ENOMEM;
+
 	return cnt;
 }
 
-- 
2.55.0.229.g6434b31f56-goog