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From: Andrew Morton <akpm@linux-foundation.org>
To: yi.y.yang@intel.com
Cc: gregkh@suse.de, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2.6.24] Add new string functions strict_strto* and convert kernel params to use them, take 2
Date: Thu, 31 Jan 2008 23:36:26 -0800	[thread overview]
Message-ID: <20080131233626.2a91d534.akpm@linux-foundation.org> (raw)
In-Reply-To: <1201817503.3925.5.camel@yangyi-dev.bj.intel.com>

On Fri, 01 Feb 2008 06:11:43 +0800 Yi Yang <yi.y.yang@intel.com> wrote:

> This patch is a resend, it changes previous name "real_" to "strict_" 
> according to Randy Dunlap's feedback. Please consider to apply. thanks.
> 
> Currently, for every sysfs node, the callers will be responsible for
> implementing store operation, so many many callers are doing duplicate
> things to validate input, they have the same mistakes because they are
> calling simple_strtol/ul/ll/uul, especially for module params, they are
> just numeric, but you can echo such values as 0x1234xxx, 07777888 and
> 1234aaa, for these cases, module params store operation just ignores
> succesive invalid char and converts prefix part to a numeric although
> input is acctually invalid.
> 
> This patch tries to fix the aforementioned issues and implements strict_strtox
> serial functions, kernel/params.c uses them to strictly validate input,
> so module params will reject such values as 0x1234xxxx and returns an error:
> 
> write error: Invalid argument
> 
> Any modules which export numeric sysfs node can use strict_strtox instead of
> simple_strtox to reject any invalid input.
> 
> Here are some test results:
> 
> Before applying this patch:
> 
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 0x1000 > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 0x1000g > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 0x1000gggggggg > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 010000 > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 0100008 > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 010000aaaaa > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]#
> 
> 
> After applying this patch:
> 
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 0x1000 > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 0x1000g > /sys/module/e1000/parameters/copybreak
> -bash: echo: write error: Invalid argument
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo 0x1000gggggggg > /sys/module/e1000/parameters/copybreak
> -bash: echo: write error: Invalid argument
> [root@yangyi-dev /]# echo 010000 > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# echo 0100008 > /sys/module/e1000/parameters/copybreak
> -bash: echo: write error: Invalid argument
> [root@yangyi-dev /]# echo 010000aaaaa > /sys/module/e1000/parameters/copybreak
> -bash: echo: write error: Invalid argument
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]# echo -n 4096 > /sys/module/e1000/parameters/copybreak
> [root@yangyi-dev /]# cat /sys/module/e1000/parameters/copybreak
> 4096
> [root@yangyi-dev /]#
> 

Oh dear.  So if someone has an existing script which does

	echo 0x1000g > /sys/module/e1000/parameters/copybreak

we just broke their setup.

This is what happens when we screw up kernel interfaces: we should remain
bug-for-bug compatible with earlier releases.  argh, we suck :(

I'm inclined to merge it anyway - everyone already knows we suck, and
not many people will be affected and they suck too.


  parent reply	other threads:[~2008-02-01  7:38 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-04 10:10 [linux-pm][PATCH] base: Change power/wakeup output from "" to "unsupported" if wakeup feature isn't supported by a device Yi Yang
2008-01-04 11:48 ` Pavel Machek
2008-01-04 16:09   ` David Brownell
2008-01-04 16:38     ` Alan Stern
2008-01-04 16:52       ` Olivier Galibert
2008-01-04 17:20         ` Oliver Neukum
2008-01-07  2:00           ` Yi Yang
2008-01-07  1:55         ` Yi Yang
2008-01-07  3:49           ` David Brownell
2008-01-07  1:52       ` Yi Yang
2008-01-07  1:37     ` Yi Yang
2008-01-07  1:57       ` Rafael J. Wysocki
2008-01-07  2:05         ` Yi Yang
2008-01-07 16:46           ` Rafael J. Wysocki
2008-01-07  1:21   ` Yi Yang
2008-01-04 16:31 ` David Brownell
2008-01-07  1:51   ` Yi Yang
2008-01-22 23:05 ` [PATCH 2.6.24-rc8] cpufreq: fix obvious condition statement error Yi Yang
2008-01-28 23:14   ` [PATCH 2.6.24] x86: add sysfs interface for cpuid module Yi Yang
2008-01-29  8:44     ` Sam Ravnborg
2008-01-29 22:22       ` Yi Yang
2008-01-30  7:48         ` Sam Ravnborg
2008-01-29 15:51     ` H. Peter Anvin
2008-01-29 17:52       ` Yi Yang
2008-01-30  6:09         ` H. Peter Anvin
2008-01-29 21:56       ` Yi Yang
2008-01-30  7:17         ` H. Peter Anvin
2008-01-29 22:13           ` Yi Yang
2008-01-30  7:33             ` H. Peter Anvin
2008-01-29 23:41     ` [RFC PATCH 2.6.24] x86: add sysfs interface for cpuid module, try 2 Yi Yang
2008-01-30 17:35       ` H. Peter Anvin
2008-01-31  1:18       ` [PATCH 2.6.24] Add new string functions real_strtoul and change kernel params to use them Yi Yang
2008-01-31 17:03         ` Randy Dunlap
2008-01-31 16:30           ` Yi Yang
2008-02-01  2:47             ` Randy Dunlap
2008-01-31 22:11         ` [PATCH 2.6.24] Add new string functions strict_strto* and convert kernel params to use them, take 2 Yi Yang
2008-02-01  0:02           ` [PATCH 2.6.24] Add new string functions strict_strto* and convert kernel params to use them, take 3 Yi Yang
2008-02-01  7:36           ` Andrew Morton [this message]
2008-02-01  7:39           ` [PATCH 2.6.24] Add new string functions strict_strto* and convert kernel params to use them, take 2 Andrew Morton
2008-02-01  7:40           ` Andrew Morton
2008-02-01 16:31     ` [PATCH 2.6.24] x86: add sysfs interface for cpuid module dean gaudet
2008-02-01 17:56       ` H. Peter Anvin
2008-02-01 17:58         ` H. Peter Anvin
2008-02-14 23:44   ` [PATCH 2.6.25-rc1] cpufreq: fix cpufreq policy refcount imbalance Yi Yang
2008-02-14 23:48   ` Yi Yang
2008-02-15 15:52     ` [linux-pm] " Alan Stern
2008-02-15 18:24       ` Greg KH
2008-02-15 21:01     ` Greg KH
2008-02-25  0:46     ` [PATCH 2.6.25-rc3] cpuidle: fix cpuidle time and usage overflow Yi Yang
2008-02-25 10:15       ` Ingo Molnar
2008-02-25  1:10         ` Yi Yang
2008-03-26  4:46       ` Len Brown

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