params: Fix potential memory leak in add_sysfs_param()
On allocation failure, it would fail to free the old attrs array which
was no longer referenced by anything (since it would free the old
module_param_attrs struct on the way out).
Comment the suspicious-looking krealloc() usage to explain why it *isn't*
actually buggy, despite looking like a classic realloc() usage bug.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/kernel/params.c b/kernel/params.c
index ed35345..53b958f 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -613,10 +613,13 @@
sizeof(*mk->mp) + sizeof(mk->mp->attrs[0]) * (num+1),
GFP_KERNEL);
if (!new) {
- kfree(mk->mp);
+ kfree(attrs);
err = -ENOMEM;
goto fail;
}
+ /* Despite looking like the typical realloc() bug, this is safe.
+ * We *want* the old 'attrs' to be freed either way, and we'll store
+ * the new one in the success case. */
attrs = krealloc(attrs, sizeof(new->grp.attrs[0])*(num+2), GFP_KERNEL);
if (!attrs) {
err = -ENOMEM;