linux-kernel - Re: [PATCH bpf] bpf: harden flags check in cgroup_storage_update

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Message-ID: <2b829425-96c7-aa51-d783-f727c4ef96d6@iogearbox.net>
Date:   Fri, 28 Sep 2018 15:53:10 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Roman Gushchin <guro@...com>, netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com,
        Alexei Starovoitov <ast@...nel.org>
Subject: Re: [PATCH bpf] bpf: harden flags check in
 cgroup_storage_update_elem()

On 09/28/2018 03:33 PM, Roman Gushchin wrote:
> cgroup_storage_update_elem() shouldn't accept any flags
> argument values except BPF_ANY and BPF_EXIST to guarantee
> the backward compatibility, had a new flag value been added.
> 
> Fixes: de9cbbaadba5 ("bpf: introduce cgroup storage maps")
> Signed-off-by: Roman Gushchin <guro@...com>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Daniel Borkmann <daniel@...earbox.net>
> ---
>  kernel/bpf/local_storage.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
> index f8746e6a9a35..2a7680106320 100644
> --- a/kernel/bpf/local_storage.c
> +++ b/kernel/bpf/local_storage.c
> @@ -130,7 +130,7 @@ static int cgroup_storage_update_elem(struct bpf_map *map, void *_key,
>  	struct bpf_cgroup_storage *storage;
>  	struct bpf_storage_buffer *new;
>  
> -	if (flags & BPF_NOEXIST)
> +	if (flags != BPF_ANY && flags != BPF_EXIST)
>  		return -EINVAL;
>  
>  	storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
> 

Applied to bpf, thanks!