* [PATCH stable 4.9] posix-timers: Sanitize overrun handling
@ 2018-11-01 20:02 Florian Fainelli
2018-11-07 19:37 ` Florian Fainelli
0 siblings, 1 reply; 5+ messages in thread
From: Florian Fainelli @ 2018-11-01 20:02 UTC (permalink / raw)
To: linux-kernel
Cc: stable, gregkh, Thomas Gleixner, Peter Zijlstra, Michael Kerrisk,
Florian Fainelli, John Stultz
From: Thomas Gleixner <tglx@linutronix.de>
[ Upstream commit 78c9c4dfbf8c04883941445a195276bb4bb92c76 ]
The posix timer overrun handling is broken because the forwarding functions
can return a huge number of overruns which does not fit in an int. As a
consequence timer_getoverrun(2) and siginfo::si_overrun can turn into
random number generators.
The k_clock::timer_forward() callbacks return a 64 bit value now. Make
k_itimer::ti_overrun[_last] 64bit as well, so the kernel internal
accounting is correct. 3Remove the temporary (int) casts.
Add a helper function which clamps the overrun value returned to user space
via timer_getoverrun(2) or siginfo::si_overrun limited to a positive value
between 0 and INT_MAX. INT_MAX is an indicator for user space that the
overrun value has been clamped.
Reported-by: Team OWL337 <icytxw@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Link: https://lkml.kernel.org/r/20180626132705.018623573@linutronix.de
[florian: Make patch apply to v4.9.135]
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
Thomas, can you review for correctness? Thanks!
include/linux/posix-timers.h | 4 ++--
kernel/time/posix-cpu-timers.c | 2 +-
kernel/time/posix-timers.c | 29 +++++++++++++++++++----------
3 files changed, 22 insertions(+), 13 deletions(-)
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index 62d44c176071..e4b8678183f5 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -65,8 +65,8 @@ struct k_itimer {
spinlock_t it_lock;
clockid_t it_clock; /* which timer type */
timer_t it_id; /* timer id */
- int it_overrun; /* overrun on pending signal */
- int it_overrun_last; /* overrun on last delivered signal */
+ s64 it_overrun; /* overrun on pending signal */
+ s64 it_overrun_last; /* overrun on last delivered signal */
int it_requeue_pending; /* waiting to requeue this timer */
#define REQUEUE_PENDING 1
int it_sigev_notify; /* notify word of sigevent struct */
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 39008d78927a..21a27bb73587 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -103,7 +103,7 @@ static void bump_cpu_timer(struct k_itimer *timer,
continue;
timer->it.cpu.expires += incr;
- timer->it_overrun += 1 << i;
+ timer->it_overrun += 1LL << i;
delta -= incr;
}
}
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index fc7c37ad90a0..0e6ed2e7d066 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -355,6 +355,17 @@ static __init int init_posix_timers(void)
__initcall(init_posix_timers);
+/*
+ * The siginfo si_overrun field and the return value of timer_getoverrun(2)
+ * are of type int. Clamp the overrun value to INT_MAX
+ */
+static inline int timer_overrun_to_int(struct k_itimer *timr, int baseval)
+{
+ s64 sum = timr->it_overrun_last + (s64)baseval;
+
+ return sum > (s64)INT_MAX ? INT_MAX : (int)sum;
+}
+
static void schedule_next_timer(struct k_itimer *timr)
{
struct hrtimer *timer = &timr->it.real.timer;
@@ -362,12 +373,11 @@ static void schedule_next_timer(struct k_itimer *timr)
if (timr->it.real.interval.tv64 == 0)
return;
- timr->it_overrun += (unsigned int) hrtimer_forward(timer,
- timer->base->get_time(),
- timr->it.real.interval);
+ timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(),
+ timr->it.real.interval);
timr->it_overrun_last = timr->it_overrun;
- timr->it_overrun = -1;
+ timr->it_overrun = -1LL;
++timr->it_requeue_pending;
hrtimer_restart(timer);
}
@@ -396,7 +406,7 @@ void do_schedule_next_timer(struct siginfo *info)
else
schedule_next_timer(timr);
- info->si_overrun += timr->it_overrun_last;
+ info->si_overrun = timer_overrun_to_int(timr, info->si_overrun);
}
if (timr)
@@ -491,8 +501,7 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
now = ktime_add(now, kj);
}
#endif
- timr->it_overrun += (unsigned int)
- hrtimer_forward(timer, now,
+ timr->it_overrun += hrtimer_forward(timer, now,
timr->it.real.interval);
ret = HRTIMER_RESTART;
++timr->it_requeue_pending;
@@ -633,7 +642,7 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
it_id_set = IT_ID_SET;
new_timer->it_id = (timer_t) new_timer_id;
new_timer->it_clock = which_clock;
- new_timer->it_overrun = -1;
+ new_timer->it_overrun = -1LL;
if (timer_event_spec) {
if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
@@ -762,7 +771,7 @@ common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
*/
if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
timr->it_sigev_notify == SIGEV_NONE))
- timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
+ timr->it_overrun += hrtimer_forward(timer, now, iv);
remaining = __hrtimer_expires_remaining_adjusted(timer, now);
/* Return 0 only, when the timer is expired and not pending */
@@ -824,7 +833,7 @@ SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
if (!timr)
return -EINVAL;
- overrun = timr->it_overrun_last;
+ overrun = timer_overrun_to_int(timr, 0);
unlock_timer(timr, flags);
return overrun;
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH stable 4.9] posix-timers: Sanitize overrun handling
2018-11-01 20:02 [PATCH stable 4.9] posix-timers: Sanitize overrun handling Florian Fainelli
@ 2018-11-07 19:37 ` Florian Fainelli
2018-11-08 6:48 ` Thomas Gleixner
0 siblings, 1 reply; 5+ messages in thread
From: Florian Fainelli @ 2018-11-07 19:37 UTC (permalink / raw)
To: linux-kernel, Thomas Gleixner, John Stultz
Cc: stable, gregkh, Peter Zijlstra, Michael Kerrisk
On 11/1/18 1:02 PM, Florian Fainelli wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> [ Upstream commit 78c9c4dfbf8c04883941445a195276bb4bb92c76 ]
>
> The posix timer overrun handling is broken because the forwarding functions
> can return a huge number of overruns which does not fit in an int. As a
> consequence timer_getoverrun(2) and siginfo::si_overrun can turn into
> random number generators.
>
> The k_clock::timer_forward() callbacks return a 64 bit value now. Make
> k_itimer::ti_overrun[_last] 64bit as well, so the kernel internal
> accounting is correct. 3Remove the temporary (int) casts.
>
> Add a helper function which clamps the overrun value returned to user space
> via timer_getoverrun(2) or siginfo::si_overrun limited to a positive value
> between 0 and INT_MAX. INT_MAX is an indicator for user space that the
> overrun value has been clamped.
>
> Reported-by: Team OWL337 <icytxw@gmail.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Acked-by: John Stultz <john.stultz@linaro.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Michael Kerrisk <mtk.manpages@gmail.com>
> Link: https://lkml.kernel.org/r/20180626132705.018623573@linutronix.de
> [florian: Make patch apply to v4.9.135]
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
> Thomas, can you review for correctness? Thanks!
Thomas, John, does that look like a reasonable backport for 4.9?
>
> include/linux/posix-timers.h | 4 ++--
> kernel/time/posix-cpu-timers.c | 2 +-
> kernel/time/posix-timers.c | 29 +++++++++++++++++++----------
> 3 files changed, 22 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
> index 62d44c176071..e4b8678183f5 100644
> --- a/include/linux/posix-timers.h
> +++ b/include/linux/posix-timers.h
> @@ -65,8 +65,8 @@ struct k_itimer {
> spinlock_t it_lock;
> clockid_t it_clock; /* which timer type */
> timer_t it_id; /* timer id */
> - int it_overrun; /* overrun on pending signal */
> - int it_overrun_last; /* overrun on last delivered signal */
> + s64 it_overrun; /* overrun on pending signal */
> + s64 it_overrun_last; /* overrun on last delivered signal */
> int it_requeue_pending; /* waiting to requeue this timer */
> #define REQUEUE_PENDING 1
> int it_sigev_notify; /* notify word of sigevent struct */
> diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
> index 39008d78927a..21a27bb73587 100644
> --- a/kernel/time/posix-cpu-timers.c
> +++ b/kernel/time/posix-cpu-timers.c
> @@ -103,7 +103,7 @@ static void bump_cpu_timer(struct k_itimer *timer,
> continue;
>
> timer->it.cpu.expires += incr;
> - timer->it_overrun += 1 << i;
> + timer->it_overrun += 1LL << i;
> delta -= incr;
> }
> }
> diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
> index fc7c37ad90a0..0e6ed2e7d066 100644
> --- a/kernel/time/posix-timers.c
> +++ b/kernel/time/posix-timers.c
> @@ -355,6 +355,17 @@ static __init int init_posix_timers(void)
>
> __initcall(init_posix_timers);
>
> +/*
> + * The siginfo si_overrun field and the return value of timer_getoverrun(2)
> + * are of type int. Clamp the overrun value to INT_MAX
> + */
> +static inline int timer_overrun_to_int(struct k_itimer *timr, int baseval)
> +{
> + s64 sum = timr->it_overrun_last + (s64)baseval;
> +
> + return sum > (s64)INT_MAX ? INT_MAX : (int)sum;
> +}
> +
> static void schedule_next_timer(struct k_itimer *timr)
> {
> struct hrtimer *timer = &timr->it.real.timer;
> @@ -362,12 +373,11 @@ static void schedule_next_timer(struct k_itimer *timr)
> if (timr->it.real.interval.tv64 == 0)
> return;
>
> - timr->it_overrun += (unsigned int) hrtimer_forward(timer,
> - timer->base->get_time(),
> - timr->it.real.interval);
> + timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(),
> + timr->it.real.interval);
>
> timr->it_overrun_last = timr->it_overrun;
> - timr->it_overrun = -1;
> + timr->it_overrun = -1LL;
> ++timr->it_requeue_pending;
> hrtimer_restart(timer);
> }
> @@ -396,7 +406,7 @@ void do_schedule_next_timer(struct siginfo *info)
> else
> schedule_next_timer(timr);
>
> - info->si_overrun += timr->it_overrun_last;
> + info->si_overrun = timer_overrun_to_int(timr, info->si_overrun);
> }
>
> if (timr)
> @@ -491,8 +501,7 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
> now = ktime_add(now, kj);
> }
> #endif
> - timr->it_overrun += (unsigned int)
> - hrtimer_forward(timer, now,
> + timr->it_overrun += hrtimer_forward(timer, now,
> timr->it.real.interval);
> ret = HRTIMER_RESTART;
> ++timr->it_requeue_pending;
> @@ -633,7 +642,7 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
> it_id_set = IT_ID_SET;
> new_timer->it_id = (timer_t) new_timer_id;
> new_timer->it_clock = which_clock;
> - new_timer->it_overrun = -1;
> + new_timer->it_overrun = -1LL;
>
> if (timer_event_spec) {
> if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
> @@ -762,7 +771,7 @@ common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
> */
> if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
> timr->it_sigev_notify == SIGEV_NONE))
> - timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
> + timr->it_overrun += hrtimer_forward(timer, now, iv);
>
> remaining = __hrtimer_expires_remaining_adjusted(timer, now);
> /* Return 0 only, when the timer is expired and not pending */
> @@ -824,7 +833,7 @@ SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
> if (!timr)
> return -EINVAL;
>
> - overrun = timr->it_overrun_last;
> + overrun = timer_overrun_to_int(timr, 0);
> unlock_timer(timr, flags);
>
> return overrun;
>
--
Florian
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH stable 4.9] posix-timers: Sanitize overrun handling
2018-11-07 19:37 ` Florian Fainelli
@ 2018-11-08 6:48 ` Thomas Gleixner
2018-11-08 15:46 ` Sasha Levin
0 siblings, 1 reply; 5+ messages in thread
From: Thomas Gleixner @ 2018-11-08 6:48 UTC (permalink / raw)
To: Florian Fainelli
Cc: linux-kernel, John Stultz, stable, gregkh, Peter Zijlstra,
Michael Kerrisk
Florian,
On Wed, 7 Nov 2018, Florian Fainelli wrote:
> On 11/1/18 1:02 PM, Florian Fainelli wrote:
> > From: Thomas Gleixner <tglx@linutronix.de>
> >
> > [ Upstream commit 78c9c4dfbf8c04883941445a195276bb4bb92c76 ]
> >
> > The posix timer overrun handling is broken because the forwarding functions
> > can return a huge number of overruns which does not fit in an int. As a
> > consequence timer_getoverrun(2) and siginfo::si_overrun can turn into
> > random number generators.
> >
> > The k_clock::timer_forward() callbacks return a 64 bit value now. Make
> > k_itimer::ti_overrun[_last] 64bit as well, so the kernel internal
> > accounting is correct. 3Remove the temporary (int) casts.
> >
> > Add a helper function which clamps the overrun value returned to user space
> > via timer_getoverrun(2) or siginfo::si_overrun limited to a positive value
> > between 0 and INT_MAX. INT_MAX is an indicator for user space that the
> > overrun value has been clamped.
> >
> > Reported-by: Team OWL337 <icytxw@gmail.com>
> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> > Acked-by: John Stultz <john.stultz@linaro.org>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Michael Kerrisk <mtk.manpages@gmail.com>
> > Link: https://lkml.kernel.org/r/20180626132705.018623573@linutronix.de
> > [florian: Make patch apply to v4.9.135]
> > Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> > ---
> > Thomas, can you review for correctness? Thanks!
>
> Thomas, John, does that look like a reasonable backport for 4.9?
Looks correct.
Thanks,
tglx
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH stable 4.9] posix-timers: Sanitize overrun handling
2018-11-08 6:48 ` Thomas Gleixner
@ 2018-11-08 15:46 ` Sasha Levin
2018-11-08 22:36 ` Florian Fainelli
0 siblings, 1 reply; 5+ messages in thread
From: Sasha Levin @ 2018-11-08 15:46 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Florian Fainelli, linux-kernel, John Stultz, stable, gregkh,
Peter Zijlstra, Michael Kerrisk
On Thu, Nov 08, 2018 at 07:48:16AM +0100, Thomas Gleixner wrote:
>Florian,
>
>On Wed, 7 Nov 2018, Florian Fainelli wrote:
>> On 11/1/18 1:02 PM, Florian Fainelli wrote:
>> > From: Thomas Gleixner <tglx@linutronix.de>
>> >
>> > [ Upstream commit 78c9c4dfbf8c04883941445a195276bb4bb92c76 ]
>> >
>> > The posix timer overrun handling is broken because the forwarding functions
>> > can return a huge number of overruns which does not fit in an int. As a
>> > consequence timer_getoverrun(2) and siginfo::si_overrun can turn into
>> > random number generators.
>> >
>> > The k_clock::timer_forward() callbacks return a 64 bit value now. Make
>> > k_itimer::ti_overrun[_last] 64bit as well, so the kernel internal
>> > accounting is correct. 3Remove the temporary (int) casts.
>> >
>> > Add a helper function which clamps the overrun value returned to user space
>> > via timer_getoverrun(2) or siginfo::si_overrun limited to a positive value
>> > between 0 and INT_MAX. INT_MAX is an indicator for user space that the
>> > overrun value has been clamped.
>> >
>> > Reported-by: Team OWL337 <icytxw@gmail.com>
>> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>> > Acked-by: John Stultz <john.stultz@linaro.org>
>> > Cc: Peter Zijlstra <peterz@infradead.org>
>> > Cc: Michael Kerrisk <mtk.manpages@gmail.com>
>> > Link: https://lkml.kernel.org/r/20180626132705.018623573@linutronix.de
>> > [florian: Make patch apply to v4.9.135]
>> > Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
>> > ---
>> > Thomas, can you review for correctness? Thanks!
>>
>> Thomas, John, does that look like a reasonable backport for 4.9?
>
>Looks correct.
Queued for 4.9, thanks all.
--
Thanks,
Sasha
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH stable 4.9] posix-timers: Sanitize overrun handling
2018-11-08 15:46 ` Sasha Levin
@ 2018-11-08 22:36 ` Florian Fainelli
0 siblings, 0 replies; 5+ messages in thread
From: Florian Fainelli @ 2018-11-08 22:36 UTC (permalink / raw)
To: Sasha Levin, Thomas Gleixner
Cc: linux-kernel, John Stultz, stable, gregkh, Peter Zijlstra,
Michael Kerrisk
On 11/8/18 7:46 AM, Sasha Levin wrote:
> On Thu, Nov 08, 2018 at 07:48:16AM +0100, Thomas Gleixner wrote:
>> Florian,
>>
>> On Wed, 7 Nov 2018, Florian Fainelli wrote:
>>> On 11/1/18 1:02 PM, Florian Fainelli wrote:
>>> > From: Thomas Gleixner <tglx@linutronix.de>
>>> >
>>> > [ Upstream commit 78c9c4dfbf8c04883941445a195276bb4bb92c76 ]
>>> >
>>> > The posix timer overrun handling is broken because the forwarding
>>> functions
>>> > can return a huge number of overruns which does not fit in an int.
>>> As a
>>> > consequence timer_getoverrun(2) and siginfo::si_overrun can turn into
>>> > random number generators.
>>> >
>>> > The k_clock::timer_forward() callbacks return a 64 bit value now. Make
>>> > k_itimer::ti_overrun[_last] 64bit as well, so the kernel internal
>>> > accounting is correct. 3Remove the temporary (int) casts.
>>> >
>>> > Add a helper function which clamps the overrun value returned to
>>> user space
>>> > via timer_getoverrun(2) or siginfo::si_overrun limited to a
>>> positive value
>>> > between 0 and INT_MAX. INT_MAX is an indicator for user space that the
>>> > overrun value has been clamped.
>>> >
>>> > Reported-by: Team OWL337 <icytxw@gmail.com>
>>> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>>> > Acked-by: John Stultz <john.stultz@linaro.org>
>>> > Cc: Peter Zijlstra <peterz@infradead.org>
>>> > Cc: Michael Kerrisk <mtk.manpages@gmail.com>
>>> > Link: https://lkml.kernel.org/r/20180626132705.018623573@linutronix.de
>>> > [florian: Make patch apply to v4.9.135]
>>> > Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
>>> > ---
>>> > Thomas, can you review for correctness? Thanks!
>>>
>>> Thomas, John, does that look like a reasonable backport for 4.9?
>>
>> Looks correct.
>
> Queued for 4.9, thanks all.
Thanks, the same patch should be applicable to earlier kernel versions
as well with little to no hunks. At least I applied it as far back as
4.1 so far. I could provide a patch for earlier kernels that did not
have the file renaming.
--
Florian
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-11-08 22:37 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-11-01 20:02 [PATCH stable 4.9] posix-timers: Sanitize overrun handling Florian Fainelli
2018-11-07 19:37 ` Florian Fainelli
2018-11-08 6:48 ` Thomas Gleixner
2018-11-08 15:46 ` Sasha Levin
2018-11-08 22:36 ` Florian Fainelli
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).