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From: Kees Cook <keescook@chromium.org>
To: Michal Hocko <mhocko@suse.com>
Cc: Xiaoming Ni <nixiaoming@huawei.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, mcgrof@kernel.org,
	yzaikin@google.com, adobriyan@gmail.com,
	linux-fsdevel@vger.kernel.org, vbabka@suse.cz,
	wangle6@huawei.com
Subject: Re: [PATCH v2] proc_sysctl: fix oops caused by incorrect command parameters.
Date: Mon, 11 Jan 2021 11:50:49 -0800	[thread overview]
Message-ID: <202101111149.20A58E1@keescook> (raw)
In-Reply-To: <20210111142131.GA22493@dhcp22.suse.cz>

On Mon, Jan 11, 2021 at 03:21:31PM +0100, Michal Hocko wrote:
> On Mon 11-01-21 11:48:19, Xiaoming Ni wrote:
> [...]
> > patch3:
> > 	+++ b/fs/proc/proc_sysctl.c
> > 	@@ -1770,6 +1770,9 @@ static int process_sysctl_arg(char *param, char *val,
> > 							return 0;
> > 			}
> > 
> > 	+       if (!val)
> > 	+               return -EINVAL;
> > 	+
> > 			/*
> > 			 * To set sysctl options, we use a temporary mount of proc, look up the
> > 			 * respective sys/ file and write to it. To avoid mounting it when no
> > 
> > sysctl log for patch3:
> > 	Setting sysctl args: `' invalid for parameter `hung_task_panic'
> [...]
> > When process_sysctl_arg() is called, the param parameter may not be the
> > sysctl parameter.
> > 
> > Patch3 or patch4, which is better?
> 
> Patch3

Oh, I see the issue here -- I thought we were only calling
process_sysctl_arg() with valid sysctl fields. It looks like we're not,
which means it should silently ignore everything that isn't a sysctl
field, and only return -EINVAL when it IS a sysctl but it lacks a value.

-- 
Kees Cook

  reply	other threads:[~2021-01-11 19:51 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-08  2:33 [PATCH v2] proc_sysctl: fix oops caused by incorrect command parameters Xiaoming Ni
2021-01-08  9:21 ` Michal Hocko
2021-01-08 10:01   ` Xiaoming Ni
2021-01-08 11:47     ` Michal Hocko
2021-01-08 19:56       ` Kees Cook
2021-01-08 20:10         ` Michal Hocko
2021-01-09  1:50           ` Andrew Morton
2021-01-11  3:48             ` Xiaoming Ni
2021-01-11 14:21               ` Michal Hocko
2021-01-11 19:50                 ` Kees Cook [this message]
     [not found] ` <CAHp75Vfdyh1ad7p_-uqYZPyF78tOB96HKNQVXkOv_yrReo2Mcg@mail.gmail.com>
2021-01-11  3:14   ` Xiaoming Ni

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