linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Xiaoming Ni <nixiaoming@huawei.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.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 11:48:19 +0800	[thread overview]
Message-ID: <bc098af4-c0cd-212e-d09d-46d617d0acab@huawei.com> (raw)
In-Reply-To: <20210108175008.da3c60a6e402f5f1ddab2a65@linux-foundation.org>

On 2021/1/9 9:50, Andrew Morton wrote:
> On Fri, 8 Jan 2021 21:10:25 +0100 Michal Hocko <mhocko@suse.com> wrote:
> 
>>>> Why would that matter? A missing value is clearly a error path and it
>>>> should be reported.
>>>
>>> This test is in the correct place. I think it's just a question of the
>>> return values.
>>
>> I was probably not clear. The test for val is at the right place. I
>> would just expect -EINVAL and have the generic code to report.
> 
> It does seem a bit screwy that process_sysctl_arg() returns zero in all
> situations (parse_args() is set up to handle an error return from it).
> But this patch is consistent with all the other error handling in
> process_sysctl_arg().
> .
> 


Set the kernel startup parameter to "nosmp nokaslr hung_task_panic"
and test the startup logs of different patches.

patch1:
	+++ b/fs/proc/proc_sysctl.c
	@@ -1757,6 +1757,11 @@ static int process_sysctl_arg(char *param, char 
*val,
			loff_t pos = 0;
			ssize_t wret;

	+       if (!val) {
	+               pr_err("Missing param value! Expected 
'%s=...value...'\n", param);
	+               return 0;
	+       }
	+
			if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
					param += sizeof("sysctl") - 1;

sysctl log for patch1:
	Missing param value! Expected 'nosmp=...value...'
	Missing param value! Expected 'nokaslr=...value...'
	Missing param value! Expected 'hung_task_panic=...value...'

patch2:
	+++ b/fs/proc/proc_sysctl.c
	@@ -1756,6 +1756,8 @@ static int process_sysctl_arg(char *param, char *val,
			int err;
			loff_t pos = 0;
			ssize_t wret;
	+       if (!val)
	+               return -EINVAL;

			if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
					param += sizeof("sysctl") - 1;

sysctl log for patch2:
	Setting sysctl args: `' invalid for parameter `nosmp'
	Setting sysctl args: `' invalid for parameter `nokaslr'
	Setting sysctl args: `' invalid for parameter `hung_task_panic'

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'

patch4:
	+++ b/fs/proc/proc_sysctl.c
	@@ -1757,6 +1757,9 @@ static int process_sysctl_arg(char *param, char *val,
			loff_t pos = 0;
			ssize_t wret;

	+       if (!val)
	+               return 0;
	+
			if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
					param += sizeof("sysctl") - 1;

sysctl log for patch3:
	no log

When process_sysctl_arg() is called, the param parameter may not be the 
sysctl parameter.

Patch3 or patch4, which is better?

Thanks
Xiaoming Ni


  reply	other threads:[~2021-01-11  3:49 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 [this message]
2021-01-11 14:21               ` Michal Hocko
2021-01-11 19:50                 ` Kees Cook
     [not found] ` <CAHp75Vfdyh1ad7p_-uqYZPyF78tOB96HKNQVXkOv_yrReo2Mcg@mail.gmail.com>
2021-01-11  3:14   ` Xiaoming Ni

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=bc098af4-c0cd-212e-d09d-46d617d0acab@huawei.com \
    --to=nixiaoming@huawei.com \
    --cc=adobriyan@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=keescook@chromium.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mcgrof@kernel.org \
    --cc=mhocko@suse.com \
    --cc=vbabka@suse.cz \
    --cc=wangle6@huawei.com \
    --cc=yzaikin@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).