From: "Luck, Tony" <tony.luck@intel.com>
To: Aili Yao <yaoaili@kingsoft.com>, Borislav Petkov <bp@alien8.de>
Cc: "x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"Andy Lutomirski" <luto@kernel.org>,
"HORIGUCHI NAOYA( 堀口 直也)" <naoya.horiguchi@nec.com>
Subject: RE: [RFC 0/4] Fix machine check recovery for copy_from_user
Date: Thu, 8 Apr 2021 14:39:09 +0000 [thread overview]
Message-ID: <595ed0ac4fbb470ca9cfd256aaf1810e@intel.com> (raw)
In-Reply-To: <20210408101335.28fd3692@alex-virtual-machine>
> I have one scenario, may you take into account:
>
> If one copyin case occurs, write() returned by your patch, the user process may
> check the return values, for errors, it may exit the process, then the error page
> will be freed, and then the page maybe alloced to other process or to kernel itself,
> then code will initialize it and this will trigger one SRAO, if it's used by kernel,
> we may do nothing for this, and kernel may still touch it, and lead to one panic.
In this case kill_me_never() calls memory_failure() with flags == 0. I think (hope!)
that means that it will unmap the page from the task, but will not send a signal.
When the task exits the PTE for this page has the swap/poison signature, so the
page is not freed for re-use.
-Tony
next prev parent reply other threads:[~2021-04-08 14:39 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 0:02 [RFC 0/4] Fix machine check recovery for copy_from_user Tony Luck
2021-03-26 0:02 ` [PATCH 1/4] x86/mce: Fix copyin code to return -EFAULT on machine check Tony Luck
2021-04-06 19:24 ` Borislav Petkov
2021-03-26 0:02 ` [PATCH 2/4] mce/iter: Check for copyin failure & return error up stack Tony Luck
2021-03-26 0:02 ` [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison Tony Luck
2021-04-07 21:18 ` Borislav Petkov
2021-04-07 21:43 ` Luck, Tony
2021-04-08 8:49 ` Borislav Petkov
2021-04-08 17:08 ` Luck, Tony
2021-04-13 10:07 ` Borislav Petkov
2021-04-13 16:13 ` Luck, Tony
2021-04-14 13:05 ` Borislav Petkov
2021-03-26 0:02 ` [PATCH 4/4] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-04-08 13:36 ` Borislav Petkov
2021-04-08 16:06 ` Luck, Tony
2021-04-08 2:13 ` [RFC 0/4] Fix machine check recovery for copy_from_user Aili Yao
2021-04-08 14:39 ` Luck, Tony [this message]
2021-04-09 6:49 ` Aili Yao
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