Commit 75bd665c authored Jun 26, 2006 by Andi Kleen Committed by Linus Torvalds Jun 26, 2006

[PATCH] x86_64: Fix fast check in safe_smp_processor_id



The APIC ID returned by hard_smp_processor_id can be beyond
NR_CPUS and then overflow the x86_cpu_to_apic[] array.

Add a check for overflow. If it happens then the slow loop below
will catch.

Bug pointed out by Doug Thompson

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent e42f9437

arch/x86_64/kernel/smp.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -520,13 +520,13 @@ asmlinkage void smp_call_function_interrupt(void)

		int safe_smp_processor_id(void)
		{
		int apicid, i;
		unsigned apicid, i;

		if (disable_apic)
		return 0;

		apicid = hard_smp_processor_id();
		if (x86_cpu_to_apicid[apicid] == apicid)
		if (apicid < NR_CPUS && x86_cpu_to_apicid[apicid] == apicid)
		return apicid;

		for (i = 0; i < NR_CPUS; ++i) {

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