netdev - Re: [PATCH bpf v2 1/3] bpf: don't assume build-id length is always 20 bytes

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Message-ID: <748aa350-11a7-5928-8a92-2afe6ecee3a8@iogearbox.net>
Date:   Thu, 17 Jan 2019 16:55:55 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Stanislav Fomichev <sdf@...gle.com>, netdev@...r.kernel.org
Cc:     davem@...emloft.net, ast@...nel.org, songliubraving@...com
Subject: Re: [PATCH bpf v2 1/3] bpf: don't assume build-id length is always 20
 bytes

On 01/16/2019 11:03 PM, Stanislav Fomichev wrote:
> Build-id length is not fixed to 20, it can be (`man ld` /--build-id):
>   * 128-bit (uuid)
>   * 160-bit (sha1)
>   * any length specified in ld --build-id=0xhexstring
> 
> To fix the issue of missing BPF_STACK_BUILD_ID_VALID for shorter build-ids,
> assume that build-id is somewhere in the range of 1 .. 20.
> Set the remaining bytes to zero.
> 
> v2:
> * don't introduce new "len = min(BPF_BUILD_ID_SIZE, nhdr->n_descsz)",
>   we already know that nhdr->n_descsz <= BPF_BUILD_ID_SIZE if we enter
>   this 'if' condition
> 
> Fixes: 615755a77b24 ("bpf: extend stackmap to save binary_build_id+offset instead of address")
> Acked-by: Song Liu <songliubraving@...com>
> Signed-off-by: Stanislav Fomichev <sdf@...gle.com>

Series applied, thanks!