netdev - Re: [PATCH net] net/sched: tcindex: search key must be 16 bits

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Message-ID: <CANn89iKbvzS0VHa2oxrNQ5MgD1Sv_2wznYrjr+kc3Xq6X-npwA@mail.gmail.com>
Date:   Wed, 15 Feb 2023 10:36:38 +0100
From:   Eric Dumazet <edumazet@...gle.com>
To:     Pedro Tammela <pctammela@...atatu.com>
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com
Subject: Re: [PATCH net] net/sched: tcindex: search key must be 16 bits

On Tue, Feb 14, 2023 at 2:47 AM Pedro Tammela <pctammela@...atatu.com> wrote:
>
> Syzkaller found an issue where a handle greater than 16 bits would trigger
> a null-ptr-deref in the imperfect hash area update.
>
>
> Fixes: ee059170b1f7 ("net/sched: tcindex: update imperfect hash filters respecting rcu")
> Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
> Signed-off-by: Pedro Tammela <pctammela@...atatu.com>

Reported-by: syzbot <syzkaller@...glegroups.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>

> ---
>  net/sched/cls_tcindex.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c
> index ba7f22a49..6640e75ea 100644
> --- a/net/sched/cls_tcindex.c
> +++ b/net/sched/cls_tcindex.c
> @@ -503,7 +503,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
>                 /* lookup the filter, guaranteed to exist */
>                 for (cf = rcu_dereference_bh_rtnl(*fp); cf;
>                      fp = &cf->next, cf = rcu_dereference_bh_rtnl(*fp))
> -                       if (cf->key == handle)
> +                       if (cf->key == (u16)handle)
>                                 break;
>
>                 f->next = cf->next;
> --
> 2.34.1
>