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Date:   Fri, 8 Oct 2021 18:10:26 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Lorenzo Bianconi <lorenzo@kernel.org>
Cc:     bpf@vger.kernel.org, netdev@vger.kernel.org,
        lorenzo.bianconi@redhat.com, davem@davemloft.net, ast@kernel.org,
        daniel@iogearbox.net, shayagr@amazon.com, john.fastabend@gmail.com,
        dsahern@kernel.org, brouer@redhat.com, echaudro@redhat.com,
        jasowang@redhat.com, alexander.duyck@gmail.com, saeed@kernel.org,
        maciej.fijalkowski@intel.com, magnus.karlsson@intel.com,
        tirthendu.sarkar@intel.com, toke@redhat.com
Subject: Re: [PATCH v15 bpf-next 17/18] net: xdp: introduce bpf_xdp_pointer
 utility routine
Message-ID: <20211008181026.0b94149a@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
In-Reply-To: <911989270cd187c98a65edabc709eb1f49af3e51.1633697183.git.lorenzo@kernel.org>
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        <911989270cd187c98a65edabc709eb1f49af3e51.1633697183.git.lorenzo@kernel.org>
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On Fri,  8 Oct 2021 14:49:55 +0200 Lorenzo Bianconi wrote:
> +BPF_CALL_4(bpf_xdp_load_bytes, struct xdp_buff *, xdp, u32, offset,
> +	   void *, buf, u32, len)
> +{
> +	void *ptr;
> +
> +	if (!buf)
> +		return -EINVAL;

Can we make the verifier ensure it's not NULL?

> +	ptr = bpf_xdp_pointer(xdp, offset, len, buf);
> +	if (ptr != buf)
> +		memcpy(buf, ptr, len);

Don't we need to return an error in case offset + length > frame size?

> +	return 0;
> +}