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

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: 8c3ba8d049 ("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
This commit is contained in:
Colin Ian King 2019-06-19 19:14:46 +01:00 committed by Thomas Gleixner
parent 32f010deab
commit ea136a112d
1 changed files with 2 additions and 1 deletions
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3
arch/x86/kernel/apic/apic.c
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@ -1464,7 +1464,8 @@ 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--;
}