Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
minimum bound on the alarm timer interval. This minimum bound shouldn't
be applied if the interval is 0. Otherwise, one-shot timers will be
converted into periodic ones.
This patch is against 4.9.39, and is only needed in -stable trees.
4.13-rc2 isn't impacted due to a later refactoring.
Fixes: ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals")
Reported-by: Ben Fennema <[email protected]>
Signed-off-by: Greg Hackmann <[email protected]>
Cc: [email protected]
---
kernel/time/alarmtimer.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 9ba04aa740b9..d67ef56ca9bc 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -629,7 +629,8 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,
* Rate limit to the tick as a hot fix to prevent DOS. Will be
* mopped up later.
*/
- if (ktime_to_ns(timr->it.alarm.interval) < TICK_NSEC)
+ if (timr->it.alarm.interval.tv64 &&
+ ktime_to_ns(timr->it.alarm.interval) < TICK_NSEC)
timr->it.alarm.interval = ktime_set(0, TICK_NSEC);
exp = timespec_to_ktime(new_setting->it_value);
--
2.14.0.rc0.284.gd933b75aa4-goog
On Mon, Jul 24, 2017 at 10:19:24AM -0700, Greg Hackmann wrote:
> Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
> minimum bound on the alarm timer interval. This minimum bound shouldn't
> be applied if the interval is 0. Otherwise, one-shot timers will be
> converted into periodic ones.
>
> This patch is against 4.9.39, and is only needed in -stable trees.
> 4.13-rc2 isn't impacted due to a later refactoring.
What refactoring patch fixed this up?
> Fixes: ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals")
As this was a 4.12 patch, 4.12-stable needs this fix as well, right?
Also, was there some test-case that you caught this with that perhaps
could be added to LTP or kselftests?
thanks,
greg k-h
On 07/24/2017 11:21 AM, Greg KH wrote:
> On Mon, Jul 24, 2017 at 10:19:24AM -0700, Greg Hackmann wrote:
>> Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
>> minimum bound on the alarm timer interval. This minimum bound shouldn't
>> be applied if the interval is 0. Otherwise, one-shot timers will be
>> converted into periodic ones.
>>
>> This patch is against 4.9.39, and is only needed in -stable trees.
>> 4.13-rc2 isn't impacted due to a later refactoring.
>
> What refactoring patch fixed this up?
f2c45807d399 ("alarmtimer: Switch over to generic set/get/rearm routine")
> As this was a 4.12 patch, 4.12-stable needs this fix as well, right?
Looks like it, but I haven't actually tried 4.12 yet to confirm.
> Also, was there some test-case that you caught this with that perhaps
> could be added to LTP or kselftests?
Unfortunately not a direct testcase. This first showed up as a
regression in AOSP's userspace Bluetooth stack, which uses
CLOCK_BOOTTIME_ALARM internally.
I'm working on a patch to add one-shot timer testcases to
set-timer-lat.c, which would have caught this. (I wrote a very rough
test program to make sure this patch fixes the regression, but
set-timer-lat.c already exists and is more comprehensive.)
On Mon, Jul 24, 2017 at 02:41:10PM -0700, Greg Hackmann wrote:
> On 07/24/2017 11:21 AM, Greg KH wrote:
> > On Mon, Jul 24, 2017 at 10:19:24AM -0700, Greg Hackmann wrote:
> > > Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
> > > minimum bound on the alarm timer interval. This minimum bound shouldn't
> > > be applied if the interval is 0. Otherwise, one-shot timers will be
> > > converted into periodic ones.
> > >
> > > This patch is against 4.9.39, and is only needed in -stable trees.
> > > 4.13-rc2 isn't impacted due to a later refactoring.
> >
> > What refactoring patch fixed this up?
>
> f2c45807d399 ("alarmtimer: Switch over to generic set/get/rearm routine")
Ick, yeah, that's not a stable patch :)
> > As this was a 4.12 patch, 4.12-stable needs this fix as well, right?
>
> Looks like it, but I haven't actually tried 4.12 yet to confirm.
>
> > Also, was there some test-case that you caught this with that perhaps
> > could be added to LTP or kselftests?
>
> Unfortunately not a direct testcase. This first showed up as a regression
> in AOSP's userspace Bluetooth stack, which uses CLOCK_BOOTTIME_ALARM
> internally.
>
> I'm working on a patch to add one-shot timer testcases to set-timer-lat.c,
> which would have caught this. (I wrote a very rough test program to make
> sure this patch fixes the regression, but set-timer-lat.c already exists and
> is more comprehensive.)
Ok, thanks for the information.
John and Thomas, any objection for me to take the original patch here in
the stable trees to fix this issue?
thanks,
greg k-h
On Mon, 24 Jul 2017, Greg KH wrote:
> On Mon, Jul 24, 2017 at 02:41:10PM -0700, Greg Hackmann wrote:
> > On 07/24/2017 11:21 AM, Greg KH wrote:
> > > On Mon, Jul 24, 2017 at 10:19:24AM -0700, Greg Hackmann wrote:
> > > > Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
> > > > minimum bound on the alarm timer interval. This minimum bound shouldn't
> > > > be applied if the interval is 0. Otherwise, one-shot timers will be
> > > > converted into periodic ones.
> > > >
> > > > This patch is against 4.9.39, and is only needed in -stable trees.
> > > > 4.13-rc2 isn't impacted due to a later refactoring.
> > >
> > > What refactoring patch fixed this up?
> >
> > f2c45807d399 ("alarmtimer: Switch over to generic set/get/rearm routine")
>
> Ick, yeah, that's not a stable patch :)
>
> > > As this was a 4.12 patch, 4.12-stable needs this fix as well, right?
> >
> > Looks like it, but I haven't actually tried 4.12 yet to confirm.
> >
> > > Also, was there some test-case that you caught this with that perhaps
> > > could be added to LTP or kselftests?
> >
> > Unfortunately not a direct testcase. This first showed up as a regression
> > in AOSP's userspace Bluetooth stack, which uses CLOCK_BOOTTIME_ALARM
> > internally.
> >
> > I'm working on a patch to add one-shot timer testcases to set-timer-lat.c,
> > which would have caught this. (I wrote a very rough test program to make
> > sure this patch fixes the regression, but set-timer-lat.c already exists and
> > is more comprehensive.)
>
> Ok, thanks for the information.
>
> John and Thomas, any objection for me to take the original patch here in
> the stable trees to fix this issue?
No. I borked that when I was 'fixing' that DoS issue :(
Reviewed-by: Thomas Gleixner <[email protected]>
On Tue, Jul 25, 2017 at 09:00:42AM +0200, Thomas Gleixner wrote:
> On Mon, 24 Jul 2017, Greg KH wrote:
>
> > On Mon, Jul 24, 2017 at 02:41:10PM -0700, Greg Hackmann wrote:
> > > On 07/24/2017 11:21 AM, Greg KH wrote:
> > > > On Mon, Jul 24, 2017 at 10:19:24AM -0700, Greg Hackmann wrote:
> > > > > Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
> > > > > minimum bound on the alarm timer interval. This minimum bound shouldn't
> > > > > be applied if the interval is 0. Otherwise, one-shot timers will be
> > > > > converted into periodic ones.
> > > > >
> > > > > This patch is against 4.9.39, and is only needed in -stable trees.
> > > > > 4.13-rc2 isn't impacted due to a later refactoring.
> > > >
> > > > What refactoring patch fixed this up?
> > >
> > > f2c45807d399 ("alarmtimer: Switch over to generic set/get/rearm routine")
> >
> > Ick, yeah, that's not a stable patch :)
> >
> > > > As this was a 4.12 patch, 4.12-stable needs this fix as well, right?
> > >
> > > Looks like it, but I haven't actually tried 4.12 yet to confirm.
> > >
> > > > Also, was there some test-case that you caught this with that perhaps
> > > > could be added to LTP or kselftests?
> > >
> > > Unfortunately not a direct testcase. This first showed up as a regression
> > > in AOSP's userspace Bluetooth stack, which uses CLOCK_BOOTTIME_ALARM
> > > internally.
> > >
> > > I'm working on a patch to add one-shot timer testcases to set-timer-lat.c,
> > > which would have caught this. (I wrote a very rough test program to make
> > > sure this patch fixes the regression, but set-timer-lat.c already exists and
> > > is more comprehensive.)
> >
> > Ok, thanks for the information.
> >
> > John and Thomas, any objection for me to take the original patch here in
> > the stable trees to fix this issue?
>
> No. I borked that when I was 'fixing' that DoS issue :(
>
> Reviewed-by: Thomas Gleixner <[email protected]>
Thanks for the review.
Greg, can you provide a version of this for 4.12-stable? It doesn't
apply there as-is.
thanks,
greg k-h
Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
minimum bound on the alarm timer interval. This minimum bound shouldn't
be applied if the interval is 0. Otherwise, one-shot timers will be
converted into periodic ones.
This patch is specific to 4.11.y and 4.12.y. Older -stable trees have a
slightly different patch, and 4.13-rc2 isn't impacted due to a later
refactoring.
Fixes: ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals")
Reported-by: Ben Fennema <[email protected]>
Signed-off-by: Greg Hackmann <[email protected]>
Cc: [email protected]
---
kernel/time/alarmtimer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index ee2f4202d82a..11e70a38497c 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -665,7 +665,7 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,
* Rate limit to the tick as a hot fix to prevent DOS. Will be
* mopped up later.
*/
- if (timr->it.alarm.interval < TICK_NSEC)
+ if (timr->it.alarm.interval && timr->it.alarm.interval < TICK_NSEC)
timr->it.alarm.interval = TICK_NSEC;
exp = timespec64_to_ktime(new_setting->it_value);
--
2.14.0.rc0.284.gd933b75aa4-goog
On Tue, Jul 25, 2017 at 12:42:46PM -0700, Greg Hackmann wrote:
> Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
> minimum bound on the alarm timer interval. This minimum bound shouldn't
> be applied if the interval is 0. Otherwise, one-shot timers will be
> converted into periodic ones.
>
> This patch is specific to 4.11.y and 4.12.y. Older -stable trees have a
> slightly different patch, and 4.13-rc2 isn't impacted due to a later
> refactoring.
>
> Fixes: ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals")
> Reported-by: Ben Fennema <[email protected]>
> Signed-off-by: Greg Hackmann <[email protected]>
> Cc: [email protected]
> ---
> kernel/time/alarmtimer.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Thanks, now queued up.
greg k-h