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References: <20220122005644.802352-1-colin.foster@in-advantage.com> <20220122005644.802352-2-colin.foster@in-advantage.com>
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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Fri, 21 Jan 2022 17:13:28 -0800
Message-ID: <CAADnVQK8xrQ92+=wm8AoDkC93SEKz3G=CoOnkPgvs=spJk5UZA@mail.gmail.com>
Subject: Re: [net RFC v1 1/1] page_pool: fix NULL dereference crash
To:     Colin Foster <colin.foster@in-advantage.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.com>,
        John Fastabend <john.fastabend@gmail.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Jesper Dangaard Brouer <hawk@kernel.org>
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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)
>                 pool->p.init_callback(page, pool->p.init_arg);
>  }
>
> --
> 2.25.1
>