mm/page_alloc.c: add additional checking and return value for the 'table->data'

- check the length of the procfs data before copying it into a fixed
  size array.

- when __parse_numa_zonelist_order() fails, save the error code for
  return.

- 'char*' --> 'char *' coding style fix

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 4 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fab9506273be..a662c74a0f5d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3256,18 +3256,25 @@ 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) {