Re: [net RFC v1 1/1] page_pool: fix NULL dereference crash

Jesper Dangaard Brouer
2022-01-22T08:31:32Z

On 22/01/2022 03.40, Colin Foster wrote:
> On Fri, Jan 21, 2022 at 05:13:28PM -0800, Alexei Starovoitov wrote:
>> On Fri, Jan 21, 2022 at 4:57 PM Colin Foster
>> <colin.foster@in-advantage.com> wrote:
>>>
>>> Check for the existence of page pool params before dereferencing. This can
>>> cause crashes in certain conditions.
>>
>> In what conditions?
>> Out of tree driver?
>>
>>> Fixes: 35b2e549894b ("page_pool: Add callback to init pages when they are
>>> allocated")
>>>
>>> Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
>>> ---
>>> net/core/page_pool.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
>>> index bd62c01a2ec3..641f849c95e7 100644
>>> --- a/net/core/page_pool.c
>>> +++ b/net/core/page_pool.c
>>> @@ -213,7 +213,7 @@ static void page_pool_set_pp_info(struct page_pool *pool,
>>> {
>>> page->pp = pool;
>>> page->pp_magic |= PP_SIGNATURE;
>>> - if (pool->p.init_callback)
>>> + if (pool->p && pool->p.init_callback)
>
> And my apologies - this should be if (pool... not if (pool->p. kernelbot
> will be sure to tell me of this blunder soon

Can you confirm if your crash is fixed by this change?

>>> pool->p.init_callback(page, pool->p.init_arg);
>>> }