Re: [PATCH] params: fix potential memory leak in add_sysfs_param()

Arjun Sreedharan
2014-08-20T21:08:43Z

On 21 August 2014 02:19, Rusty Russell <rusty@rustcorp.com.au> wrote:
> Arjun Sreedharan <arjun024@gmail.com> writes:
>> Do not leak memory when attrs is non NULL and
>> krealloc() fails. Without temporary variable,
>> reference to it is lost.
>>
>> Signed-off-by: Arjun Sreedharan <arjun024@gmail.com>
>
> ...
>
>> }
>> - /* 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) {
>> +
>> + new_attrs = krealloc(attrs, sizeof(new->grp.attrs[0])*(num+2), GFP_KERNEL);
>> + if (!new_attrs) {
>
> I think that comment you deleted is pretty clear. Is it wrong?
>
> Cheers,
> Rusty.

I believe it's wrong. I do not understand how `this is safe` from memory leak.
If krealloc() fails, there is nothing in place to free memory held by @attrs