timer_create(2) should return 0 on success

The timer ID is copied out to the argument.

Fixes #1738

PiperOrigin-RevId: 293210801

2 files changed, 18 insertions, 2 deletions

diff --git a/pkg/sentry/syscalls/linux/sys_timer.go b/pkg/sentry/syscalls/linux/sys_timer.go
index 432351917..a4c400f87 100644
--- a/pkg/sentry/syscalls/linux/sys_timer.go
+++ b/pkg/sentry/syscalls/linux/sys_timer.go
@@ -146,7 +146,7 @@ func TimerCreate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.S
 		return 0, nil, err
 	}
 
-	return uintptr(id), nil, nil
+	return 0, nil, nil
 }
 
 // TimerSettime implements linux syscall timer_settime(2).
diff --git a/test/syscalls/linux/timers.cc b/test/syscalls/linux/timers.cc
index 3db18d7ac..2f92c27da 100644
--- a/test/syscalls/linux/timers.cc
+++ b/test/syscalls/linux/timers.cc
@@ -297,9 +297,13 @@ class IntervalTimer {
 PosixErrorOr<IntervalTimer> TimerCreate(clockid_t clockid,
                                         const struct sigevent& sev) {
   int timerid;
-  if (syscall(SYS_timer_create, clockid, &sev, &timerid) < 0) {
+  int ret = syscall(SYS_timer_create, clockid, &sev, &timerid);
+  if (ret < 0) {
     return PosixError(errno, "timer_create");
   }
+  if (ret > 0) {
+    return PosixError(EINVAL, "timer_create should never return positive");
+  }
   MaybeSave();
   return IntervalTimer(timerid);
 }
@@ -317,6 +321,18 @@ TEST(IntervalTimerTest, IsInitiallyStopped) {
   EXPECT_EQ(0, its.it_value.tv_nsec);
 }
 
+// Kernel can create multiple timers without issue.
+//
+// Regression test for gvisor.dev/issue/1738.
+TEST(IntervalTimerTest, MultipleTimers) {
+  struct sigevent sev = {};
+  sev.sigev_notify = SIGEV_NONE;
+  const auto timer1 =
+      ASSERT_NO_ERRNO_AND_VALUE(TimerCreate(CLOCK_MONOTONIC, sev));
+  const auto timer2 =
+      ASSERT_NO_ERRNO_AND_VALUE(TimerCreate(CLOCK_MONOTONIC, sev));
+}
+
 TEST(IntervalTimerTest, SingleShotSilent) {
   struct sigevent sev = {};
   sev.sigev_notify = SIGEV_NONE;