diff --git a/hw/intc/sifive_clint.c b/hw/intc/sifive_clint.c index 0f41e5ea1c..99c870ced2 100644 --- a/hw/intc/sifive_clint.c +++ b/hw/intc/sifive_clint.c @@ -59,8 +59,29 @@ static void sifive_clint_write_timecmp(RISCVCPU *cpu, uint64_t value, riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(0)); diff = cpu->env.timecmp - rtc_r; /* back to ns (note args switched in muldiv64) */ - next = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + - muldiv64(diff, NANOSECONDS_PER_SECOND, timebase_freq); + uint64_t ns_diff = muldiv64(diff, NANOSECONDS_PER_SECOND, timebase_freq); + + /* + * check if ns_diff overflowed and check if the addition would potentially + * overflow + */ + if ((NANOSECONDS_PER_SECOND > timebase_freq && ns_diff < diff) || + ns_diff > INT64_MAX) { + next = INT64_MAX; + } else { + /* + * as it is very unlikely qemu_clock_get_ns will return a value + * greater than INT64_MAX, no additional check is needed for an + * unsigned integer overflow. + */ + next = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns_diff; + /* + * if ns_diff is INT64_MAX next may still be outside the range + * of a signed integer. + */ + next = MIN(next, INT64_MAX); + } + timer_mod(cpu->env.timer, next); }