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From: Boris Sukholitko <boris.sukholitko@broadcom.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org, keescook@chromium.org,
	yzaikin@google.com
Subject: Re: [PATCH] __register_sysctl_table: do not drop subdir
Date: Sun, 31 May 2020 14:39:33 +0300	[thread overview]
Message-ID: <20200531113933.GA22327@noodle> (raw)
In-Reply-To: <874ks02m25.fsf@x220.int.ebiederm.org>

On Thu, May 28, 2020 at 09:04:02AM -0500, Eric W. Biederman wrote:

[snip incorrect root cause analysis]

> 
> But the insertion of children in insert_header also increases the count
> so it does not look like that should be true.
> 

Yes, I have missed the insert_header nreg increment, thus making my root
cause analysis incorrect.

IMHO, the bug does exist in the latest kernel. Could you please see:

[PATCH] get_subdir: do not drop new subdir if returning it

I've just sent to the fsdevel mailing list. In it I've added invariant:

WARN_ON(dir->header.nreg < 2);

at the end of __register_sysctl_table which the latest kernel fails to
obey.

The fix seems to belong to get_subdir function, therefore I've broke the
thread and sent a new patch.

Thanks,
Boris.

  parent reply	other threads:[~2020-05-31 11:39 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27 10:48 [PATCH] __register_sysctl_table: do not drop subdir Boris Sukholitko
2020-05-27 12:58 ` Luis Chamberlain
2020-05-28  8:08   ` Boris Sukholitko
2020-05-28 14:04     ` Eric W. Biederman
2020-05-28 14:20       ` Luis Chamberlain
2020-05-31 11:44         ` Boris Sukholitko
2020-06-01 13:17           ` Luis Chamberlain
2020-05-31 11:39       ` Boris Sukholitko [this message]
2020-06-03  1:07 ` [__register_sysctl_table] 4092a9304d: WARNING:at_fs/proc/proc_sysctl.c:#retire_sysctl_set kernel test robot

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