linux-kernel - RE: [RFC PATCH] ACPI / EC: Fix an order issue in ec_remove

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 7 Jul 2016 04:38:52 +0000
From:	"Zheng, Lv" <lv.zheng@...el.com>
To:	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Brown, Len" <len.brown@...el.com>
CC:	Lv Zheng <zetalog@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Nicholas <nkudriavtsev@...il.com>
Subject: RE: [RFC PATCH] ACPI / EC: Fix an order issue in
 ec_remove_handlers()

This one and the previous one contain problems.
A patch marked as [UPDATE RFC v2] is the correct fix.
Sorry for the noise.

Thanks and best regards
-Lv

> From: Zheng, Lv
> Subject: [RFC PATCH] ACPI / EC: Fix an order issue in ec_remove_handlers()
> 
> There is an order issue in ec_remove_handlers() that the functions invoked
> in it are not invoked in the reversed order of their appearance in
> ec_install_handlers(). This existing issue has been triggered by the
> following commit:
>   Commit: dcf15cbded656a12335bc4151f3f75f10080a375
>   Subject: ACPI / EC: Fix a boot EC regresion by restoring boot EC
> The commit invokes ec_remove_handlers() during runtime, thus uncovers
> this
> issue. This patch fixes this regression.
> 
> Fixes: dcf15cbded65 ("ACPI / EC: Fix a boot EC regresion by restoring boot
> EC")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=102421
> Reported-by: Wolfram Sang <wsa@...-dreams.de>
> Reported-by: Nicholas <nkudriavtsev@...il.com>
> Cc: Wolfram Sang <wsa@...-dreams.de>
> Cc: Nicholas <nkudriavtsev@...il.com>
> Signed-off-by: Lv Zheng <lv.zheng@...el.com>
> ---
>  drivers/acpi/ec.c |   14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> Index: linux-acpica/drivers/acpi/ec.c
> ==========================================================
> =========
> --- linux-acpica.orig/drivers/acpi/ec.c
> +++ linux-acpica/drivers/acpi/ec.c
> @@ -1331,8 +1331,6 @@ static int ec_install_handlers(struct ac
> 
>  static void ec_remove_handlers(struct acpi_ec *ec)
>  {
> -	acpi_ec_stop(ec, false);
> -
>  	if (test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
>  		if (ACPI_FAILURE(acpi_remove_address_space_handler(ec-
> >handle,
>  					ACPI_ADR_SPACE_EC,
> &acpi_ec_space_handler)))
> @@ -1340,6 +1338,17 @@ static void ec_remove_handlers(struct ac
>  		clear_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
>  	}
> 
> +	/*
> +	 * Disabling EC (transactions) after removing the operation region
> +	 * handler. This order is required because _REG(DISCONNECT) may
> +	 * access the EmbeddedControl operation regions.
> +	 *
> +	 * Flushing transactions before removing the GPE handler. This is
> +	 * required by the current ACPICA GPE design. ACPICA GPE will
> block
> +	 * a GPE if there is no way to handle it.
> +	 */
> +	acpi_ec_stop(ec, false);
> +
>  	if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
>  		if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
>  					&acpi_ec_gpe_handler)))