[PATCH] mm/page_alloc.c: add additional checking and return valuefor the 'table->data'

[Chen Gang]

If 'table->data' is invalid, also need check its length to know whether
is invalid, firstly.

When __parse_numa_zonelist_order() fails, also need save the related
error code for return.

Beautify code ('char*' --> 'char *') to pass "./scripts/checkpatch.pl"


Signed-off-by: Chen Gang <gang.chen@xxxxxxxxxxx>
---
 mm/page_alloc.c |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0a0acfe..48c83e4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3250,18 +3250,25 @@ int numa_zonelist_order_handler(ctl_table *table, int write,
 	static DEFINE_MUTEX(zl_order_mutex);
 
 	mutex_lock(&zl_order_mutex);
-	if (write)
-		strcpy(saved_string, (char*)table->data);
+	if (write) {
+		if (strlen((char *)table->data) >= NUMA_ZONELIST_ORDER_LEN) {
+			ret = -EINVAL;
+			goto out;
+		}
+		strcpy(saved_string, (char *)table->data);
+	}
 	ret = proc_dostring(table, write, buffer, length, ppos);
 	if (ret)
 		goto out;
 	if (write) {
 		int oldval = user_zonelist_order;
-		if (__parse_numa_zonelist_order((char*)table->data)) {
+
+		ret = __parse_numa_zonelist_order((char *)table->data);
+		if (ret) {
 			/*
 			 * bogus value.  restore saved string
 			 */
-			strncpy((char*)table->data, saved_string,
+			strncpy((char *)table->data, saved_string,
 				NUMA_ZONELIST_ORDER_LEN);
 			user_zonelist_order = oldval;
 		} else if (oldval != user_zonelist_order) {
-- 
1.7.7.6
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