Commit 2a6ee369 authored Jun 19, 2019 by Colin Ian King Committed by Greg Kroah-Hartman Jul 21, 2019

x86/apic: Fix integer overflow on 10 bit left shift of cpu_khz



[ Upstream commit ea136a112d89bade596314a1ae49f748902f4727 ]

The left shift of unsigned int cpu_khz will overflow for large values of
cpu_khz, so cast it to a long long before shifting it to avoid overvlow.
For example, this can happen when cpu_khz is 4194305, i.e. ~4.2 GHz.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 8c3ba8d0 ("x86, apic: ack all pending irqs when crashed/on kexec")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: kernel-janitors@vger.kernel.org
Link: https://lkml.kernel.org/r/20190619181446.13635-1-colin.king@canonical.com


Signed-off-by: Sasha Levin <sashal@kernel.org>

parent fdfff855

arch/x86/kernel/apic/apic.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1452,7 +1452,8 @@ static void apic_pending_intr_clear(void)
		if (queued) {
		if (boot_cpu_has(X86_FEATURE_TSC) && cpu_khz) {
		ntsc = rdtsc();
		max_loops = (cpu_khz << 10) - (ntsc - tsc);
		max_loops = (long long)cpu_khz << 10;
		max_loops -= ntsc - tsc;
		} else {
		max_loops--;
		}