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A few fixes for timers/timekeeping:

Browse source 
- Prevent undefined behaviour in the timespec64_to_ns() conversion which
     is used for converting user supplied time input to nanoseconds. It
     lacked overflow protection.
 
   - Mark sched_clock_read_begin/retry() to prevent recursion in the tracer
 
   - Remove unused debug functions in the hrtimer and timerlist code
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Merge tag 'timers-urgent-2020-11-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fixes from Thomas Gleixner:
 "A few fixes for timers/timekeeping:

   - Prevent undefined behaviour in the timespec64_to_ns() conversion
     which is used for converting user supplied time input to
     nanoseconds. It lacked overflow protection.

   - Mark sched_clock_read_begin/retry() to prevent recursion in the
     tracer

   - Remove unused debug functions in the hrtimer and timerlist code"

* tag 'timers-urgent-2020-11-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  time: Prevent undefined behaviour in timespec64_to_ns()
  timers: Remove unused inline funtion debug_timer_free()
  hrtimer: Remove unused inline function debug_hrtimer_free()
  time/sched_clock: Mark sched_clock_read_begin/retry() as notrace
This commit is contained in:
Linus Torvalds 2020-11-01 11:13:45 -08:00
commit 4312e0e8d3
5 changed files with 6 additions and 16 deletions
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4
include/linux/time64.h
View file

@ -124,6 +124,10 @@ static inline bool timespec64_valid_settod(const struct timespec64 *ts)
*/
static inline s64 timespec64_to_ns(const struct timespec64 *ts)
{
/* Prevent multiplication overflow */
if ((unsigned long long)ts->tv_sec >= KTIME_SEC_MAX)
return KTIME_MAX;
return ((s64) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
}

5
kernel/time/hrtimer.c
View file

@ -425,11 +425,6 @@ static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
debug_object_deactivate(timer, &hrtimer_debug_descr);
}
static inline void debug_hrtimer_free(struct hrtimer *timer)
{
debug_object_free(timer, &hrtimer_debug_descr);
}
static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
enum hrtimer_mode mode);

4
kernel/time/itimer.c
View file

@ -172,10 +172,6 @@ static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
u64 oval, nval, ointerval, ninterval;
struct cpu_itimer *it = &tsk->signal->it[clock_id];
/*
* Use the to_ktime conversion because that clamps the maximum
* value to KTIME_MAX and avoid multiplication overflows.
*/
nval = timespec64_to_ns(&value->it_value);
ninterval = timespec64_to_ns(&value->it_interval);

4
kernel/time/sched_clock.c
View file

@ -68,13 +68,13 @@ static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
return (cyc * mult) >> shift;
}
struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
notrace struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
{
*seq = raw_read_seqcount_latch(&cd.seq);
return cd.read_data + (*seq & 1);
}
int sched_clock_read_retry(unsigned int seq)
notrace int sched_clock_read_retry(unsigned int seq)
{
return read_seqcount_latch_retry(&cd.seq, seq);
}

5
kernel/time/timer.c
View file

@ -732,11 +732,6 @@ static inline void debug_timer_deactivate(struct timer_list *timer)
debug_object_deactivate(timer, &timer_debug_descr);
}
static inline void debug_timer_free(struct timer_list *timer)
{
debug_object_free(timer, &timer_debug_descr);
}
static inline void debug_timer_assert_init(struct timer_list *timer)
{
debug_object_assert_init(timer, &timer_debug_descr);