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params: Fix potential memory leak in add_sysfs_param()

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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>
This commit is contained in:
David Woodhouse 2013-03-14 13:23:11 +00:00
parent fe9ab00f83
commit 63662139e5
1 changed files with 4 additions and 1 deletions
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5
kernel/params.c
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@ -613,10 +613,13 @@ static __modinit int add_sysfs_param(struct module_kobject *mk,
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;