linux-kernel - Re: [PATCH v3 1/2] x86/sgx: Do not fail on incomplete sanitization on premature stop of ksgxd

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Date:   Tue, 6 Sep 2022 10:01:50 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "linux-sgx@...r.kernel.org" <linux-sgx@...r.kernel.org>,
        "jarkko@...nel.org" <jarkko@...nel.org>
CC:     "pmenzel@...gen.mpg.de" <pmenzel@...gen.mpg.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "Dhanraj, Vijay" <vijay.dhanraj@...el.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "x86@...nel.org" <x86@...nel.org>,
        "haitao.huang@...ux.intel.com" <haitao.huang@...ux.intel.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "hpa@...or.com" <hpa@...or.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] x86/sgx: Do not fail on incomplete sanitization on
 premature stop of ksgxd

On Tue, 2022-09-06 at 03:02 +0300, Jarkko Sakkinen wrote:
> Unsanitized pages trigger WARN_ON() unconditionally, which can panic the
> whole computer, if /proc/sys/kernel/panic_on_warn is set.
> 
> In sgx_init(), if misc_register() fails or misc_register() succeeds but
> neither sgx_drv_init() nor sgx_vepc_init() succeeds, then ksgxd will be
> prematurely stopped. This may leave unsanitized pages, which will result a
> false warning.
> 
> Refine __sgx_sanitize_pages() to return:
> 
> 1. Zero when the sanitization process is complete or ksgxd has been
>    requested to stop.
> 2. The number of unsanitized pages otherwise.
> 
> Link: https://lore.kernel.org/linux-sgx/20220825051827.246698-1-jarkko@kernel.org/T/#u
> Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
> Cc: stable@...r.kernel.org # v5.13+
> Reported-by: Paul Menzel <pmenzel@...gen.mpg.de>
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>

(Given the idea of moving sgx_page_reclaimer_init() to the end of sgx_init() is
considered too big to fix this bug:)

Acked-by: Kai Huang <kai.huang@...el.com>

-- 
Thanks,
-Kai