linux-kernel - Re: [RFC PATCH] cmdline: Hide "debug" from /proc/cmdline

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Date:	Wed, 02 Apr 2014 12:08:02 -0700
From:	Randy Dunlap <rdunlap@...radead.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	Ingo Molnar <mingo@...nel.org>, Mel Gorman <mgorman@...e.de>,
	Kay Sievers <kay@...y.org>
Subject: Re: [RFC PATCH] cmdline: Hide "debug" from /proc/cmdline

On 04/02/2014 12:04 PM, Andrew Morton wrote:
> On Wed, 2 Apr 2014 14:42:19 -0400 Steven Rostedt <rostedt@...dmis.org> wrote:
>
>> It has come to our attention that a system running a specific user
>> space init program will not boot if you add "debug" to the kernel
>> command line. What happens is that the user space tool parses the
>> kernel command line, and if it sees "debug" it will spit out so much
>> information that the system fails to boot. This basically renders the
>> "debug" option for the kernel useless.
>>
>> This bug has been reported to the developers of said tool
>> here:
>>
>>    https://bugs.freedesktop.org/show_bug.cgi?id=76935
>>
>> The response is:
>>
>> "Generic terms are generic, not the first user owns them."
>>
>> That is, the "debug" statement on the *kernel* command line is not
>> owned by the kernel just because it was the first user of it, and
>> they refuse to fix their bug.
>>
>> Well, my response is, we OWN the kernel command line, and as such, we
>> can keep the users from seeing stuff on it if we so choose. And with
>> that, I propose this patch, which hides "debug" from /proc/cmdline,
>> such that we don't have to worry about tools parsing for it and causing
>> hardship for those trying to debug the kernel.
>>
>
> I had to check the date on this but surprisingly, it's all post
> April 1.
>
> --- a/fs/read_write.c~a
> +++ a/fs/read_write.c
> @@ -513,6 +513,8 @@ SYSCALL_DEFINE3(read, unsigned int, fd,
>   	struct fd f = fdget_pos(fd);
>   	ssize_t ret = -EBADF;
>
> +	BUG_ON(!strcmp(current->comm, "systemd"));
> +
>   	if (f.file) {
>   		loff_t pos = file_pos_read(f.file);
>   		ret = vfs_read(f.file, buf, count, &pos);
> _

Ack here.

This situation is ridiculous.


-- 
~Randy
--
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