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SubjectRe: [PATCH v2] vfio: Clear the caps->buf to NULL after free
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Cornelia Huck <cohuck@redhat.com> writes:

> On Tue, Jun 28 2022, Alex Williamson
> <alex.williamson@redhat.com> wrote:
>
>> On Tue, 28 Jun 2022 23:24:29 +0800
>> Schspa Shi <schspa@gmail.com> wrote:
>>
>>> API vfio_info_cap_add will free caps->buf, clear it to NULL
>>> after
>>> free.
>>
>> Should this be something like:
>>
>> On buffer resize failure, vfio_info_cap_add() will free the
>> buffer,
>> report zero for the size, and return -ENOMEM. As
>> additional
>> hardening, also clear the buffer pointer to prevent any
>> chance of a
>> double free.
>
> I like that better. With that,
>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
>

I have send a V3 patch for this comment change, please review it.

>>
>> Thanks,
>> Alex
>>
>>> Signed-off-by: Schspa Shi <schspa@gmail.com>
>>> ---
>>> drivers/vfio/vfio.c | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>>> index 61e71c1154be..a0fb93866f61 100644
>>> --- a/drivers/vfio/vfio.c
>>> +++ b/drivers/vfio/vfio.c
>>> @@ -1812,6 +1812,7 @@ struct vfio_info_cap_header
>>> *vfio_info_cap_add(struct vfio_info_cap *caps,
>>> buf = krealloc(caps->buf, caps->size + size, GFP_KERNEL);
>>> if (!buf) {
>>> kfree(caps->buf);
>>> + caps->buf = NULL;
>>> caps->size = 0;
>>> return ERR_PTR(-ENOMEM);
>>> }

--
BRs
Schspa Shi

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