linux-kernel - Re: [PATCH v7 2/4] include: Set tsk->comm length to 64 bytes

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Message-ID: <6af1a8b5-1c10-06b1-a368-a685a7e21e15@igalia.com>
Date: Wed, 13 Aug 2025 15:59:55 +0530
From: Bhupesh Sharma <bhsharma@...lia.com>
To: Andy Shevchenko <andriy.shevchenko@...el.com>,
 Bhupesh <bhupesh@...lia.com>
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Subject: Re: [PATCH v7 2/4] include: Set tsk->comm length to 64 bytes



On 8/11/25 8:40 PM, Andy Shevchenko wrote:
> On Mon, Aug 11, 2025 at 12:16:07PM +0530, Bhupesh wrote:
>> Historically due to the 16-byte length of TASK_COMM_LEN, the
>> users of 'tsk->comm' are restricted to use a fixed-size target
>> buffer also of TASK_COMM_LEN for 'memcpy()' like use-cases.
>>
>> To fix the same, we now use a 64-byte TASK_COMM_EXT_LEN and
>> set the comm element inside 'task_struct' to the same length:
>>         struct task_struct {
>> 	       .....
>>                 char    comm[TASK_COMM_EXT_LEN];
>> 	       .....
>>         };
>>
>>         where TASK_COMM_EXT_LEN is 64-bytes.
>>
>> Note, that the existing users have not been modified to migrate to
>> 'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of
>> dealing with only a 'TASK_COMM_LEN' long 'tsk->comm'.
> ...
>
>> -	BUILD_BUG_ON(sizeof(from) != TASK_COMM_LEN);	\
>> +	BUILD_BUG_ON(sizeof(from) < TASK_COMM_LEN);	\
> Wondering if we may convert this to static_assert().
> (rather in a separate patch)

That's a fair suggestion. If others don't have an objection to the 
suggested change, I can club it in v8 along with any other requested 
changes.

Thanks.