1 files changed, 23 insertions, 2 deletions
diff --git a/hw/intc/sifive_clint.c b/hw/intc/sifive_clint.c
index 0f41e5e..99c870c 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);
 }