linux-kernel - Re: [PATCH] kobject: Fix global-out-of-bounds in kobject_action

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Message-ID: <50e3be73-5fb1-0505-6ddb-422cee6e466b@huawei.com>
Date:   Tue, 7 Mar 2023 17:49:25 +0800
From:   Xia Fukun <xiafukun@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <prajnoha@...hat.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kobject: Fix global-out-of-bounds in
 kobject_action_type()

I know how to modify it to meet your requirements:

	for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) {
		if (strncmp(kobject_actions[action], buf, count_first) != 0)
			continue;
		if (strlen(kobject_actions[action]) > count_first)
			continue;
		if (args)
			*args = args_start;
		*type = action;
		ret = 0;
		break;
	}

So I will modify the patch and resubmit it. Please review it again

在 2023/3/7 17:27, Greg KH 写道:

> 
> On Tue, Mar 07, 2023 at 05:08:02PM +0800, Xia Fukun wrote:
>> Thanks for your reply.
>> Your understanding is correct."offline\0\0\0\0\0\0\0\0\0\0" is indeed blocked
>> from matching "offline" and returns a failed result.
>>
>> I'm not sure whether to relax the restrictions to make it match successfully.
>> After all, the incoming count is too large and not the actual length of
>> "offline".
> 
> But that doesn't matter at all.  Sometimes you do not have control over
> the buffer length when writing to a file like this, what matters is the
> content of the buffer and we should stop at the first \0 as that's the
> "end of a string" in this type of api.
> 
> So your change here might break existing userspace code, and we can't do
> that, sorry.
> 
> thanks,
> 
> greg k-h