From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by smtp.subspace.kernel.org (Postfix) with ESMTPS id DC3411AA8B
	for <bpf@vger.kernel.org>; Fri,  4 Aug 2023 22:26:47 +0000 (UTC)
Received: from out-120.mta0.migadu.com (out-120.mta0.migadu.com [IPv6:2001:41d0:1004:224b::78])
	by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56D461704
	for <bpf@vger.kernel.org>; Fri,  4 Aug 2023 15:26:46 -0700 (PDT)
Message-ID: <e0e8bf3b-70af-3827-2fa3-30f3d48bcf46@linux.dev>
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1;
	t=1691188004;
	h=from:from:reply-to:subject:subject:date:date:message-id:message-id:
	 to:to:cc:cc:mime-version:mime-version:content-type:content-type:
	 content-transfer-encoding:content-transfer-encoding:
	 in-reply-to:in-reply-to:references:references;
	bh=VlHvVn8ION/wYMTcwm/zIJedCAnl/hLvcfGQJkof7IM=;
	b=AjPHjOyQGFuAhWHcOt26P+iYoIVdygHw6jC/Fj8A4P1L9PvUP3Pd+gtbD7hknbpM1+fod6
	ZEPoNOUz8mYkxOCAa7T0zaNJ9BKLb3kNZRk/NZKYSDHeGsFrFxT8TYPkBIgZjSzOrFSCE6
	mpQ3ERTp1MuW9tqdXmcoKMIvk4QiB7I=
Date: Fri, 4 Aug 2023 15:26:40 -0700
Precedence: bulk
X-Mailing-List: bpf@vger.kernel.org
List-Id: <bpf.vger.kernel.org>
List-Subscribe: <mailto:bpf+subscribe@vger.kernel.org>
List-Unsubscribe: <mailto:bpf+unsubscribe@vger.kernel.org>
MIME-Version: 1.0
Subject: Re: [PATCH bpf-next] bpf: fix bpf_dynptr_slice() to stop return an
 ERR_PTR.
Content-Language: en-US
To: thinker.li@gmail.com
Cc: sinquersw@gmail.com, kuifeng@meta.com,
 Dan Carpenter <dan.carpenter@linaro.org>,
 Alexei Starovoitov <alexei.starovoitov@gmail.com>, bpf@vger.kernel.org,
 ast@kernel.org, song@kernel.org, kernel-team@meta.com, andrii@kernel.org
References: <20230803231206.1060485-1-thinker.li@gmail.com>
X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers.
From: Martin KaFai Lau <martin.lau@linux.dev>
In-Reply-To: <20230803231206.1060485-1-thinker.li@gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Migadu-Flow: FLOW_OUT
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
	DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS,
	URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
	lindbergh.monkeyblade.net

On 8/3/23 4:12 PM, thinker.li@gmail.com wrote:
> From: Kui-Feng Lee <thinker.li@gmail.com>
> 
> Verify if the pointer obtained from bpf_xdp_pointer() is either an error or
> NULL before returning it.
> 
> The function bpf_dynptr_slice() mistakenly returned an ERR_PTR. Instead of
> solely checking for NULL, it should also verify if the pointer returned by
> bpf_xdp_pointer() is an error or NULL.
> 
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/bpf/d1360219-85c3-4a03-9449-253ea905f9d1@moroto.mountain/
> Fixes: 66e3a13e7c2c ("bpf: Add bpf_dynptr_slice and bpf_dynptr_slice_rdwr")
> Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
> ---
>   kernel/bpf/helpers.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index 56ce5008aedd..eb91cae0612a 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -2270,7 +2270,7 @@ __bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset
>   	case BPF_DYNPTR_TYPE_XDP:
>   	{
>   		void *xdp_ptr = bpf_xdp_pointer(ptr->data, ptr->offset + offset, len);
> -		if (xdp_ptr)
> +		if (!IS_ERR_OR_NULL(xdp_ptr))

Considering the earlier bpf_dynptr_check_off_len() should have avoided the 
IS_ERR() case here, I think targeting bpf-next makes sense. Applied.