Merge tag 'timers-urgent-2022-08-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fixes from Ingo Molnar:
 "Misc timer fixes:

   - fix a potential use-after-free bug in posix timers

   - correct a prototype

   - address a build warning"

* tag 'timers-urgent-2022-08-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  posix-cpu-timers: Cleanup CPU timers before freeing them during exec
  time: Correct the prototype of ns_to_kernel_old_timeval and ns_to_timespec64
  posix-timers: Make do_clock_gettime() static

fs/exec.c

@@ -1304,6 +1304,9 @@ int begin_new_exec(struct linux_binprm * bprm)
 	bprm->mm = NULL;
 
 #ifdef CONFIG_POSIX_TIMERS
+	spin_lock_irq(&me->sighand->siglock);
+	posix_cpu_timers_exit(me);
+	spin_unlock_irq(&me->sighand->siglock);
 	exit_itimers(me);
 	flush_itimer_signals();
 #endif

include/linux/time64.h

@@ -145,7 +145,7 @@ static inline s64 timespec64_to_ns(const struct timespec64 *ts)
  *
  * Returns the timespec64 representation of the nsec parameter.
  */
-extern struct timespec64 ns_to_timespec64(const s64 nsec);
+extern struct timespec64 ns_to_timespec64(s64 nsec);
 
 /**
  * timespec64_add_ns - Adds nanoseconds to a timespec64

kernel/time/posix-stubs.c

@@ -70,7 +70,7 @@ SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
 	return do_sys_settimeofday64(&new_tp, NULL);
 }
 
-int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
+static int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
 {
 	switch (which_clock) {
 	case CLOCK_REALTIME:
@@ -90,6 +90,7 @@ int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
 
 	return 0;
 }
+
 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 		struct __kernel_timespec __user *, tp)
 {

kernel/time/time.c

@@ -449,7 +449,7 @@ time64_t mktime64(const unsigned int year0, const unsigned int mon0,
 }
 EXPORT_SYMBOL(mktime64);
 
-struct __kernel_old_timeval ns_to_kernel_old_timeval(const s64 nsec)
+struct __kernel_old_timeval ns_to_kernel_old_timeval(s64 nsec)
 {
 	struct timespec64 ts = ns_to_timespec64(nsec);
 	struct __kernel_old_timeval tv;
@@ -503,7 +503,7 @@ EXPORT_SYMBOL(set_normalized_timespec64);
  *
  * Returns the timespec64 representation of the nsec parameter.
  */
-struct timespec64 ns_to_timespec64(const s64 nsec)
+struct timespec64 ns_to_timespec64(s64 nsec)
 {
 	struct timespec64 ts = { 0, 0 };
 	s32 rem;