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x86/ioapic: Prevent NULL pointer dereference in setup_ioapic_dest()

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Commit 4857c91f0d changed the way how irq affinity is setup in
setup_ioapic_dest() from using the core helper function to
unconditionally calling the irq_set_affinity() callback of the
underlying irq chip.

That results in a NULL pointer dereference for the rare case where the
underlying irq chip is lapic_chip which has no irq_set_affinity()
callback. lapic_chip is occasionally used for the timer interrupt (irq
0).

The fix is simple: Check the availability of the callback instead of
calling it unconditionally.

Fixes: 4857c91f0d "x86/ioapic: Force affinity setting in setup_ioapic_dest()"
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
This commit is contained in:
Werner Pawlitschko 2015-10-27 09:08:04 +09:00 committed by Thomas Gleixner
parent 298a96c12b
commit ababae4410
1 changed files with 3 additions and 1 deletions
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4
arch/x86/kernel/apic/io_apic.c
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@ -2547,7 +2547,9 @@ void __init setup_ioapic_dest(void)
mask = apic->target_cpus();
chip = irq_data_get_irq_chip(idata);
chip->irq_set_affinity(idata, mask, false);
/* Might be lapic_chip for irq 0 */
if (chip->irq_set_affinity)
chip->irq_set_affinity(idata, mask, false);
}
}
#endif