lkml.org 
[lkml]   [2012]   [Jul]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] x86/ioapic: Fix NULL pointer dereference on CPU hotplug after disabling irqs
Hi,

In current Linux, percpu variable `vector_irq' is not always cleared when
a CPU is offlined. If the cpu that has the disabled irqs in vector_irq is
hotplugged again, __setup_vector_irq() hits invalid irq vector and may
crash.

Commit f6175f5bfb4c partially fixes this, but was not enough in
environments with IOMMU IRQ remapper.

This bug can be reproduced as following;
# echo 0 > /sys/devices/system/cpu/cpu7/online
# modprobe -r some_driver_using_interrupts # vector_irq@cpu7 uncleared
# echo 1 > /sys/devices/system/cpu/cpu7/online # kernel may crash

This patch fixes this bug by clearing vector_irq in __fixup_irqs() when
the cpu is offlined.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Alexander Gordeev <agordeev@redhat.com>
---
arch/x86/kernel/irq.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 3dafc60..d27b27d 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -328,6 +328,7 @@ void fixup_irqs(void)
chip->irq_retrigger(data);
raw_spin_unlock(&desc->lock);
}
+ __this_cpu_write(vector_irq[vector], -1);
}
}
#endif
--
1.7.7.6
--
Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory


\
 
 \ /
  Last update: 2012-07-25 12:01    [W:0.090 / U:2.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site