Re: [PATCH] printk: fix printk.devkmsg sysctl

Borislav Petkov
2017-01-27T15:14:07Z

On Fri, Jan 27, 2017 at 02:11:46PM +0100, Rabin Vincent wrote:
> From: Rabin Vincent <rabinv@axis.com>
>
> The comment says that it doesn't want to accept trailing crap but that's
> just what it allows:

...

> @@ -177,7 +177,7 @@ int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
> * Do not accept an unknown string OR a known string with
> * trailing crap...
> */
> - if (err < 0 || (err + 1 != *lenp)) {

Grr, that's that damn '\n'

echo off > /proc/sys/kernel/printk_devkmsg

works, of course.

Ok, I don't want to relax the strncmp() above and would still like to
return the exact length compared.

So please change the check above to allow the following inputs:

<str>

or

<str>\n

I.e., a trailing, *optional*, '\n' is allowed.

This way we're accepting the two most common ways to input strings:

$ echo <str> > ...

and

$ echo -n <str> > ...

Thanks!

--
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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