| From: Colin Ian King <colin.king@canonical.com> |
| Date: Wed, 19 Jun 2019 19:14:46 +0100 |
| Subject: x86/apic: Fix integer overflow on 10 bit left shift of cpu_khz |
| |
| commit ea136a112d89bade596314a1ae49f748902f4727 upstream. |
| |
| 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: 8c3ba8d04924 ("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 |
| [bwh: Backported to 3.16: adjust context] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| arch/x86/kernel/apic/apic.c | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| --- a/arch/x86/kernel/apic/apic.c |
| +++ b/arch/x86/kernel/apic/apic.c |
| @@ -1403,7 +1403,8 @@ void setup_local_APIC(void) |
| if (queued) { |
| if (cpu_has_tsc && cpu_khz) { |
| rdtscll(ntsc); |
| - max_loops = (cpu_khz << 10) - (ntsc - tsc); |
| + max_loops = (long long)cpu_khz << 10; |
| + max_loops -= ntsc - tsc; |
| } else |
| max_loops--; |
| } |
