linux-kernel - [PATCH] ARM: Fix deadlock scenario with smp_send

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: <1373384217-26307-1-git-send-email-sboyd@codeaurora.org>
Date:	Tue,  9 Jul 2013 08:36:57 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Russell King <linux@....linux.org.uk>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] ARM: Fix deadlock scenario with smp_send_stop()

If one process calls sys_reboot and that process then stops other
CPUs while those CPUs are within a spin_lock() region we can
potentially encounter a deadlock scenario like below.

CPU 0                   CPU 1
-----                   -----
                        spin_lock(my_lock)
smp_send_stop()
 <send IPI>             handle_IPI()
                         disable_preemption/irqs
                          while(1);
 <PREEMPT>
spin_lock(my_lock) <--- Waits forever

We shouldn't attempt to run any other tasks after we send a stop
IPI to a CPU so disable preemption so that this task runs to
completion.

Reported-by: Sundarajan Srinivasan <sundaraj@...eaurora.com>
Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
---

Resending this patch now that the context has changed.

 arch/arm/kernel/process.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 7f1efcd..8bc12d7 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -206,6 +206,7 @@ void machine_shutdown(void)
  */
 void machine_halt(void)
 {
+	preempt_disable();
 	smp_send_stop();
 
 	local_irq_disable();
@@ -220,6 +221,7 @@ void machine_halt(void)
  */
 void machine_power_off(void)
 {
+	preempt_disable();
 	smp_send_stop();
 
 	if (pm_power_off)
@@ -239,6 +241,7 @@ void machine_power_off(void)
  */
 void machine_restart(char *cmd)
 {
+	preempt_disable();
 	smp_send_stop();
 
 	arm_pm_restart(reboot_mode, cmd);
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

--
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/