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| author | Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com> | 2012-07-26 19:47:32 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-07-26 15:01:17 +0200 |
| commit | 1d44b30f35a9873a65b320dd5300088fa995fd94 (patch) | |
| tree | 4ca7693f3afed97c3ef7b046b529363d06f44b08 /arch/x86/kernel/apic/io_apic.c | |
| parent | d431adfbc9b7de651f3164c6b7ffcad75805d7e4 (diff) | |
| download | lwn-1d44b30f35a9873a65b320dd5300088fa995fd94.tar.gz lwn-1d44b30f35a9873a65b320dd5300088fa995fd94.zip | |
x86/ioapic: Fix NULL pointer dereference on CPU hotplug after disabling irqs
In the current kernel, 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.
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
To fix this problem, this patch clears vector_irq in
__fixup_irqs() when the CPU is offlined.
This also reverts commit f6175f5bfb4c, which partially fixes
this bug by clearing vector in __clear_irq_vector(). But in
environments with IOMMU IRQ remapper, it could fail because
cfg->domain doesn't contain offlined CPUs. With this patch, the
fix in __clear_irq_vector() can be reverted because every
vector_irq is already cleared in __fixup_irqs() on offlined CPUs.
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Alexander Gordeev <agordeev@redhat.com>
Link: http://lkml.kernel.org/r/20120726104732.2889.19144.stgit@kvmdev
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/apic/io_apic.c')
| -rw-r--r-- | arch/x86/kernel/apic/io_apic.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 406eee784684..a6c64aaddf9a 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -1204,7 +1204,7 @@ static void __clear_irq_vector(int irq, struct irq_cfg *cfg) BUG_ON(!cfg->vector); vector = cfg->vector; - for_each_cpu(cpu, cfg->domain) + for_each_cpu_and(cpu, cfg->domain, cpu_online_mask) per_cpu(vector_irq, cpu)[vector] = -1; cfg->vector = 0; @@ -1212,7 +1212,7 @@ static void __clear_irq_vector(int irq, struct irq_cfg *cfg) if (likely(!cfg->move_in_progress)) return; - for_each_cpu(cpu, cfg->old_domain) { + for_each_cpu_and(cpu, cfg->old_domain, cpu_online_mask) { for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) { if (per_cpu(vector_irq, cpu)[vector] != irq) |