FROMLIST: Fix an integer overflow issue in the NSEC_PER_SEC constant

Bug: 444295917
Link: https://lore.kernel.org/all/20250915191944.9779-1-wakel@google.com/
Signed-off-by: Wake Liu <wakel@google.com>
Test: bazel build //common:kernel_aarch64_dist
Change-Id: I75737c02f96d686b8e9c1697a0af1fe4332e3cc6

BUILD.bazel

@@ -2409,6 +2409,7 @@ cc_library(
     name = "kselftest_timers_common_hdrs",
     hdrs = [
         "include/vdso/time64.h",
+        "tools/testing/selftests/timers/helpers.h",
     ],
     copts = _KSELFTEST_COPTS,
     includes = ["."],

tools/testing/selftests/timers/alarmtimer-suspend.c

@@ -31,8 +31,9 @@
 #include <include/vdso/time64.h>
 #include <errno.h>
 #include "../kselftest.h"
+#include "helpers.h"
 
-#define UNREASONABLE_LAT (NSEC_PER_SEC * 5) /* hopefully we resume in 5 secs */
+#define UNREASONABLE_LAT (NSEC_PER_SEC * 5LL) /* hopefully we resume in 5 secs */
 
 #define SUSPEND_SECS 15
 int alarmcount;
@@ -70,14 +71,6 @@ char *clockstring(int clockid)
 }
 
 
-long long timespec_sub(struct timespec a, struct timespec b)
-{
-	long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;
-
-	ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
-	return ret;
-}
-
 int final_ret;
 
 void sigalarm(int signo)
@@ -88,8 +81,8 @@ void sigalarm(int signo)
 	clock_gettime(alarm_clock_id, &ts);
 	alarmcount++;
 
-	delta_ns = timespec_sub(start_time, ts);
-	delta_ns -= NSEC_PER_SEC * SUSPEND_SECS * alarmcount;
+	delta_ns = timespec_sub(ts, start_time);
+	delta_ns -= (long long)NSEC_PER_SEC * SUSPEND_SECS * alarmcount;
 
 	printf("ALARM(%i): %ld:%ld latency: %lld ns ", alarmcount, ts.tv_sec,
 							ts.tv_nsec, delta_ns);

tools/testing/selftests/timers/helpers.h

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef SELFTESTS_TIMERS_HELPERS_H
+#define SELFTESTS_TIMERS_HELPERS_H
+
+#include <time.h>
+
+#ifndef NSEC_PER_SEC
+#define NSEC_PER_SEC 1000000000L
+#endif
+
+/*
+ * timespec_to_ns - Convert timespec to nanoseconds
+ */
+static inline long long timespec_to_ns(const struct timespec *ts)
+{
+	return ((long long) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
+}
+
+/*
+ * timespec_sub - Subtract two timespec values
+ *
+ * @a: first timespec
+ * @b: second timespec
+ *
+ * Returns a - b in nanoseconds.
+ */
+static inline long long timespec_sub(struct timespec a, struct timespec b)
+{
+	return timespec_to_ns(&a) - timespec_to_ns(&b);
+}
+
+#endif /* SELFTESTS_TIMERS_HELPERS_H */

tools/testing/selftests/timers/nanosleep.c

@@ -138,7 +138,7 @@ int main(int argc, char **argv)
 		fflush(stdout);
 
 		length = 10;
-		while (length <= (NSEC_PER_SEC * 10)) {
+		while (length <= (NSEC_PER_SEC * 10LL)) {
 			ret = nanosleep_test(clockid, length);
 			if (ret == UNSUPPORTED) {
 				ksft_test_result_skip("%-31s\n", clockstring(clockid));

tools/testing/selftests/timers/nsleep-lat.c

@@ -26,6 +26,7 @@
 #include <signal.h>
 #include <include/vdso/time64.h>
 #include "../kselftest.h"
+#include "helpers.h"
 
 #define UNRESONABLE_LATENCY 40000000 /* 40ms in nanosecs */
 
@@ -74,14 +75,6 @@ struct timespec timespec_add(struct timespec ts, unsigned long long ns)
 }
 
 
-long long timespec_sub(struct timespec a, struct timespec b)
-{
-	long long ret = NSEC_PER_SEC * b.tv_sec + b.tv_nsec;
-
-	ret -= NSEC_PER_SEC * a.tv_sec + a.tv_nsec;
-	return ret;
-}
-
 int nanosleep_lat_test(int clockid, long long ns)
 {
 	struct timespec start, end, target;
@@ -146,7 +139,7 @@ int main(int argc, char **argv)
 			continue;
 
 		length = 10;
-		while (length <= (NSEC_PER_SEC * 10)) {
+		while (length <= (NSEC_PER_SEC * 10LL)) {
 			ret = nanosleep_lat_test(clockid, length);
 			if (ret)
 				break;

tools/testing/selftests/timers/valid-adjtimex.c

@@ -264,16 +264,16 @@ int validate_set_offset(void)
 	if (set_offset(-NSEC_PER_SEC - 1, 1))
 		return -1;
 
-	if (set_offset(5 * NSEC_PER_SEC, 1))
+	if (set_offset(5LL * NSEC_PER_SEC, 1))
 		return -1;
 
-	if (set_offset(-5 * NSEC_PER_SEC, 1))
+	if (set_offset(-5LL * NSEC_PER_SEC, 1))
 		return -1;
 
-	if (set_offset(5 * NSEC_PER_SEC + NSEC_PER_SEC / 2, 1))
+	if (set_offset(5LL * NSEC_PER_SEC + NSEC_PER_SEC / 2, 1))
 		return -1;
 
-	if (set_offset(-5 * NSEC_PER_SEC - NSEC_PER_SEC / 2, 1))
+	if (set_offset(-5LL * NSEC_PER_SEC - NSEC_PER_SEC / 2, 1))
 		return -1;
 
 	if (set_offset(USEC_PER_SEC - 1, 0))