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Subject[PATCH] x86/apic: fix integer overflow on 10 bit right shift of cpu_khz
Date
From: Colin Ian King <colin.king@canonical.com>

The right 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 (just
less than 4.2 GHz). Also wrap line to avoid checkpatch wide line
warning.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 8c3ba8d04924 ("x86, apic: ack all pending irqs when crashed/on kexec")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
arch/x86/kernel/apic/apic.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 8956072f677d..31426126e5e0 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -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) -
+ (ntsc - tsc);
} else {
max_loops--;
}
--
2.20.1
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