linux-kernel - Re: [PATCH] audit: Use strscpy instead of memcpy when copying comm

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Message-ID: <765b4384-ab4d-c202-9efd-1138bc42e9e7@huawei.com>
Date: Thu, 1 Aug 2024 09:25:32 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: Paul Moore <paul@...l-moore.com>
CC: <eparis@...hat.com>, <audit@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] audit: Use strscpy instead of memcpy when copying comm



On 2024/7/31 23:51, Paul Moore wrote:
> On Wed, Jul 31, 2024 at 3:46 AM Jinjie Ruan <ruanjinjie@...wei.com> wrote:
>>
>> There may be random garbage beyond a string's null terminator, memcpy might
>> use the entire comm array. so avoid that possibility by using strscpy
>> instead of memcpy.
>>
>> Link: https://github.com/KSPP/linux/issues/90
>> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
>> ---
>>  kernel/auditsc.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> If you look at audit_log_pid_context() you'll see that we don't record
> the entire task::comm field, we only record up the NUL byte, so any
> garbage present after the end of the string should not make it into
> the audit record.  We use memcpy(), as opposed to any of the string
> based copy functions, as the task::comm field is relatively short and
> having to count the length of the string in addition to copying the
> string is likely more expensive than simply copying the full buffer.

Thank you very much, You're right, sorry I didn't read the code
carefully enough.

>