Re: [PATCH][next] media: venus: hfi_cmds.h: Replace one-element array with flexible-array member

From: Stanimir Varbanov <stanimir.varbanov@linaro.org>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	Stanimir Varbanov <stanimir.varbanov@linaro.org>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH][next] media: venus: hfi_cmds.h: Replace one-element array with flexible-array member
Date: Wed, 12 May 2021 14:37:57 +0300	[thread overview]
Message-ID: <b9f4cce4-f836-96a9-2efd-cb5b9151a186@linaro.org> (raw)
In-Reply-To: <6081fb66-7f43-cab4-b7ff-ce4b291b8865@embeddedor.com>

Hi,

On 5/11/21 6:44 PM, Gustavo A. R. Silva wrote:
> Hi all,
> 
> Friendly ping:
> 
> We are about to be able to globally enable -Warray-bounds and, this is one of the
> last out-of-bounds warnings in linux-next.
> 
> Could someone take this, please?

I'll take this for 5.14.

> 
> Thanks
> --
> Gustavo
> 
> On 2/10/21 16:57, Gustavo A. R. Silva wrote:
>> There is a regular need in the kernel to provide a way to declare having
>> a dynamically sized set of trailing elements in a structure. Kernel code
>> should always use “flexible array members”[1] for these cases. The older
>> style of one-element or zero-length arrays should no longer be used[2].
>>
>> Use flexible-array member in struct hfi_sys_set_property_pkt instead of
>> one-element array.
>>
>> Also, this helps with the ongoing efforts to enable -Warray-bounds and
>> fix the following warnings:
>>
>> drivers/media/platform/qcom/venus/hfi_cmds.c: In function ‘pkt_sys_coverage_config’:
>> drivers/media/platform/qcom/venus/hfi_cmds.c:57:11: warning: array subscript 1 is above array bounds of ‘u32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds]
>>    57 |  pkt->data[1] = mode;
>>       |  ~~~~~~~~~^~~
>>
>> [1] https://en.wikipedia.org/wiki/Flexible_array_member
>> [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
>>
>> Link: https://github.com/KSPP/linux/issues/79
>> Link: https://github.com/KSPP/linux/issues/109
>> Build-tested-by: kernel test robot <lkp@intel.com>
>> Link: https://lore.kernel.org/lkml/602416da.iZqae7Dbk7nyl6OY%25lkp@intel.com/
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>> ---
>>  drivers/media/platform/qcom/venus/hfi_cmds.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/platform/qcom/venus/hfi_cmds.h b/drivers/media/platform/qcom/venus/hfi_cmds.h
>> index 83705e237f1c..327ed90a2788 100644
>> --- a/drivers/media/platform/qcom/venus/hfi_cmds.h
>> +++ b/drivers/media/platform/qcom/venus/hfi_cmds.h
>> @@ -68,7 +68,7 @@ struct hfi_sys_release_resource_pkt {
>>  struct hfi_sys_set_property_pkt {
>>  	struct hfi_pkt_hdr hdr;
>>  	u32 num_properties;
>> -	u32 data[1];
>> +	u32 data[];
>>  };
>>  
>>  struct hfi_sys_get_property_pkt {
>>

-- 
regards,
Stan