Re: [PATCH 3/3] floppy: suppress UBSAN warning in setup_rw_floppy()

[Denis Efremov]

On 4/22/20 11:24 AM, Christoph Hellwig wrote:
> 
> I don't think we can just change FD_RAW_CMD_SIZE or cmd as that could
> break userspace.

The second patch adds these defines FD_RAW_CMD_SIZE, FD_RAW_REPLY_SIZE.
Currently they are not in the uapi. Ok, I will send v2.

But otherwise, yes something very much like that:
> 
>>  #define FD_RAW_CMD_SIZE 16
>>  #define FD_RAW_REPLY_SIZE 16
>> +#define FD_RAW_FULL_CMD_SIZE (FD_RAW_CMD_SIZE + 1 + FD_RAW_CMD_SIZE)
>>  
>>         unsigned char cmd_count;
>> -       unsigned char cmd[FD_RAW_CMD_SIZE];
>> -       unsigned char reply_count;
>> -       unsigned char reply[FD_RAW_REPLY_SIZE];
>> +       union {
>> +               struct {
>> +                       unsigned char cmd[FD_RAW_CMD_SIZE];
>> +                       unsigned char reply_count;
>> +                       unsigned char reply[FD_RAW_REPLY_SIZE];
>> +               };
>> +               unsigned char full_cmd[FD_RAW_FULL_CMD_SIZE];
>> +       };
> 
>>         int track;
>>
>> Denis
> ---end quoted text---
>