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

[Arjun Sreedharan]

On 21 August 2014 02:19, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
> Arjun Sreedharan <arjun024@xxxxxxxxx> 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@xxxxxxxxx>
>
> ...
>
>>       }
>> -     /* 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/