x86/ioapic: Prevent NULL pointer dereference in setup_ioapic_dest()
Commit 4857c91f0d19 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: 4857c91f0d19 "x86/ioapic: Force affinity setting in setup_ioapic_dest()"
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index bb6bfc0..4f28215 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2547,7 +2547,9 @@
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