linux-kernel - [PATCH RFC] acpi: Fix unprotected smp_processor_id() in acpi_processor_cst_has

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-next>] [day] [month] [year] [list]

Message-ID: <20120223205805.GA31838@linux.vnet.ibm.com>
Date:	Thu, 23 Feb 2012 12:58:05 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	deepthi@...ux.vnet.ibm.com
Cc:	linux-kernel@...r.kernel.org, lenb@...nel.org,
	linux-acpi@...r.kernel.org
Subject: [PATCH RFC] acpi: Fix unprotected smp_processor_id() in
 acpi_processor_cst_has_changed()

The acpi_processor_cst_has_changed() function is invoked from a
CPU_ONLINE or CPU_DEAD function, which might well execute on CPU 0
even though the CPU being hotplugged is some other CPU.  In addition,
acpi_processor_cst_has_changed() invokes smp_processor_id() without
protection, resulting in splats when onlining CPUs.

This commit therefore changes the smp_processor_id() to pr->id, as is
used elsewhere in the code, for example, in acpi_processor_add().

This works for me, but I don't claim to understand ACPI.

Signed-off-by: Paul E. McKenney <paul.mckenney@...aro.org>

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 0e8e2de..9e57b06 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1159,8 +1159,7 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr)
 	 * to make the code that updates C-States be called once.
 	 */

-	if (smp_processor_id() == 0 &&
-			cpuidle_get_driver() == &acpi_idle_driver) {
+	if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) {

 		cpuidle_pause_and_lock();
 		/* Protect against cpu-hotplug */

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/