linux-kernel - Re: [PATCH -next] firmware: arm_ffa: Fix beyond size of field warning

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Message-ID: <5979b3b7-cd42-d01a-6c8f-5df7b698b324@huawei.com>
Date: Mon, 19 Aug 2024 19:01:28 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: Sudeep Holla <sudeep.holla@....com>
CC: <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] firmware: arm_ffa: Fix beyond size of field warning



On 2024/8/19 18:35, Sudeep Holla wrote:
> On Fri, Aug 16, 2024 at 06:02:58PM +0800, Jinjie Ruan wrote:
>> An allmodconfig build of arm64 resulted in following warning:
>>
>> 	In function ‘fortify_memcpy_chk’,
>> 	    inlined from ‘export_uuid’ at ./include/linux/uuid.h:88:2,
>> 	    inlined from ‘ffa_msg_send_direct_req2’ at ./drivers/firmware/arm_ffa/driver.c:488:2:
>> 	./include/linux/fortify-string.h:571:25: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
>> 	  571 |                         __write_overflow_field(p_size_field, size);
>> 	      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> 	In function ‘fortify_memcpy_chk’,
>> 	    inlined from ‘ffa_msg_send_direct_req2’ at ./drivers/firmware/arm_ffa/driver.c:489:2:
>> 	./linux-next/include/linux/fortify-string.h:571:25: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
>> 	  571 |                         __write_overflow_field(p_size_field, size);
>> 	      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Because ffa_msg_send_direct_req2() memcpy uuid_t and struct
>> ffa_send_direct_data2 data to unsigned long dst, the copy size is 2 or
>> or 14 unsigned long which beyond size of dst size, fix it by using a temp
>> array for memcpy.
>>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
>> ---
>>  drivers/firmware/arm_ffa/driver.c | 14 ++++++++++++--
>>  1 file changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
>> index 1e3764852118..674fbe008ea6 100644
>> --- a/drivers/firmware/arm_ffa/driver.c
>> +++ b/drivers/firmware/arm_ffa/driver.c
>> @@ -480,13 +480,23 @@ static int ffa_msg_send2(u16 src_id, u16 dst_id, void *buf, size_t sz)
>>  static int ffa_msg_send_direct_req2(u16 src_id, u16 dst_id, const uuid_t *uuid,
>>  				    struct ffa_send_direct_data2 *data)
>>  {
>> +	unsigned long args_data[14];
>> +	unsigned long args_uuid[2];
>> +	unsigned long *data_ptr;
>> +
>>  	u32 src_dst_ids = PACK_TARGET_INFO(src_id, dst_id);
>>  	ffa_value_t ret, args = {
>>  		.a0 = FFA_MSG_SEND_DIRECT_REQ2, .a1 = src_dst_ids,
>>  	};
>>  
>> -	export_uuid((u8 *)&args.a2, uuid);
>> -	memcpy(&args.a4, data, sizeof(*data));
>> +	memcpy(args_uuid, uuid, sizeof(uuid_t));
>> +	args.a2 = args_uuid[0];
>> +	args.a3 = args_uuid[1];
>> +
>> +	memcpy(args_data, data, sizeof(*data));
>> +	data_ptr = &args.a4;
>> +	for (int i = 0; i < 14; i++)
>> +		*data_ptr++ = args_data[i];
>>
> 
> So we end up with double copy for both uuid and ffa_send_direct_data2 ?
> This is not correct and not needed.
> 
> Which toolchain are you using ? I got error only for memcpy which I forgot
> to push to -next, now fixed. It must appear in -next soon.

Use the newest linux-next and  `make Image ARCH=arm64
CROSS_COMPILE=aarch64-linux-gnu-`, the above compile error occurs.

>