From: Borislav Petkov <bp@alien8.de>
To: Seunghun Han <kkamagui@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tony Luck <tony.luck@intel.com>,
linux-edac@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: x86: mce: fix kernel panic when check_interval is changed
Date: Wed, 28 Feb 2018 10:32:39 +0100 [thread overview]
Message-ID: <20180228093238.GA3769@pd.tnic> (raw)
On Mon, Feb 26, 2018 at 05:05:04AM +0900, Seunghun Han wrote:
> >> It is a critical security problem because the attacker can make kernel panic
> >> by writing a value to the check_interval file in userspace, and it can be
> >> used for Denial-of-Service (DoS) attack.
> >
> > As only root can write to that file, it's not that critical of an issue,
> > but yes, this is a problem. Nice find and fix.
This is still the wrong fix. You need to:
1. check the old value of check_interval in store_int_with_restart() and
exit early if it is the same.
2. have mce_restart() grab a newly defined mutex, say, mce_sysfs_mutex
or so, which synchronizes all CPUs so that their timers get deleted and
reinitialized in the proper order.
Thx.
next reply other threads:[~2018-02-28 9:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-28 9:32 Borislav Petkov [this message]
-- strict thread matches above, loose matches on Subject: below --
2018-02-28 9:48 x86: mce: fix kernel panic when check_interval is changed Seunghun Han
2018-02-25 20:05 Seunghun Han
2018-02-23 10:52 Greg Kroah-Hartman
2018-02-23 10:42 Borislav Petkov
2018-02-23 10:13 Seunghun Han
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