netdev - Re: [PATCH bpf] bpf: fix bpf_prog_get_info_by_fd to return 0 func

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Date:   Fri, 2 Nov 2018 16:25:05 +0530
From:   Sandipan Das <sandipan@...ux.ibm.com>
To:     Daniel Borkmann <daniel@...earbox.net>, ast@...nel.org
Cc:     netdev@...r.kernel.org, Sandipan Das <sandipan@...ux.vnet.ibm.com>,
        Song Liu <songliubraving@...com>
Subject: Re: [PATCH bpf] bpf: fix bpf_prog_get_info_by_fd to return 0
 func_lens for unpriv



On 02/11/18 4:05 PM, Daniel Borkmann wrote:
> While dbecd7388476 ("bpf: get kernel symbol addresses via syscall")
> zeroed info.nr_jited_ksyms in bpf_prog_get_info_by_fd() for queries
> from unprivileged users, commit 815581c11cc2 ("bpf: get JITed image
> lengths of functions via syscall") forgot about doing so and therefore
> returns the #elems of the user set up buffer which is incorrect. It
> also needs to indicate a info.nr_jited_func_lens of zero.
> 
> Fixes: 815581c11cc2 ("bpf: get JITed image lengths of functions via syscall")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Cc: Sandipan Das <sandipan@...ux.vnet.ibm.com>
> Cc: Song Liu <songliubraving@...com>
> ---
>  kernel/bpf/syscall.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index ccb9327..1ea5ce1 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2078,6 +2078,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
>  		info.jited_prog_len = 0;
>  		info.xlated_prog_len = 0;
>  		info.nr_jited_ksyms = 0;
> +		info.nr_jited_func_lens = 0;
>  		goto done;
>  	}
> 

Looks good. Thanks for fixing this. 

- Sandipan