[PATCH v5 1/4] cgroup: implement eventfd-based generic API for notifications

Kirill A. Shutemov kirill at shutemov.name
Thu Jan 7 04:36:29 PST 2010


On Thu, Jan 7, 2010 at 3:01 AM, Paul Menage <menage at google.com> wrote:
> On Wed, Dec 30, 2009 at 7:57 AM, Kirill A. Shutemov
> <kirill at shutemov.name> wrote:
>> +
>> +       if (!IS_ERR(efile))
>> +               fput(efile);
>
> While this is OK currently, it's a bit fragile. efile starts as NULL,
> and IS_ERR(NULL) is false. So if we jump to fail: before trying to do
> the eventfd_fget() then we'll try to fput(NULL), which will oops. This
> works because we don't currently jump to fail: until after
> eventfd_fget(), but someone could add an extra setup step between the
> kzalloc() and the eventfd_fget() which could fail.

So we need to use IS_ERR_OR_NULL here instread of IS_ERR, don't we?


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