linux-kernel - [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 12:33:09 +0800
From:	Lv Zheng <lv.zheng@...el.com>
To:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>
Cc:	Lv Zheng <lv.zheng@...el.com>, Lv Zheng <zetalog@...il.com>,
	<linux-kernel@...r.kernel.org>, linux-acpi@...r.kernel.org,
	Wolfram Sang <wsa@...-dreams.de>,
	Nicholas <nkudriavtsev@...il.com>
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)))