* [patch 0/2] timers: Prevent multiplication overflow in timespec/val conversions
@ 2017-06-20 15:37 Thomas Gleixner
2017-06-20 15:37 ` [patch 1/2] itimer: Make timeval to nsec conversion range limited Thomas Gleixner
2017-06-20 15:37 ` [patch 2/2] posix-cpu-timers: Make timespec to nsec conversion safe Thomas Gleixner
0 siblings, 2 replies; 5+ messages in thread
From: Thomas Gleixner @ 2017-06-20 15:37 UTC (permalink / raw)
To: LKML; +Cc: John Stultz, Peter Zijlstra, Xishi Qiu
KASAN detected a multiplication overflow in the sys_setitimer() timeval
conversion. The same issue is possible the posix-cpu-timer sys_timer_set()
implementation.
In both cases the conversion of the tv_sec part overflows when multiplied
with NSEC_PER_SEC, i.e. 1e9.
This can be mitigated by using the timespec/val_to_ktime() helper, which
prevents the overflow and clamps the result to KTIME_MAX (~292 years).
Thanks,
tglx
^ permalink raw reply [flat|nested] 5+ messages in thread
* [patch 1/2] itimer: Make timeval to nsec conversion range limited
2017-06-20 15:37 [patch 0/2] timers: Prevent multiplication overflow in timespec/val conversions Thomas Gleixner
@ 2017-06-20 15:37 ` Thomas Gleixner
2017-06-20 19:39 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2017-06-20 15:37 ` [patch 2/2] posix-cpu-timers: Make timespec to nsec conversion safe Thomas Gleixner
1 sibling, 1 reply; 5+ messages in thread
From: Thomas Gleixner @ 2017-06-20 15:37 UTC (permalink / raw)
To: LKML; +Cc: John Stultz, Peter Zijlstra, Xishi Qiu
[-- Attachment #1: itimer--Make-timeval-to-nsec-conversion-range-limited.patch --]
[-- Type: text/plain, Size: 1476 bytes --]
The expiry time of a itimer is supplied through sys_setitimer() via a
struct timeval. The timeval is validated for correctness.
In the actual set timer implementation the timeval is converted to a
scalar nanoseconds value. If the tv_sec part of the time spec is large
enough the conversion to nanoseconds (sec * NSEC_PER_SEC) overflows 64bit.
Mitigate that by using the timeval_to_ktime() conversion function, which
checks the tv_sec part for a potential mult overflow and clamps the result
to KTIME_MAX, which is about 292 years.
Reported-by: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/itimer.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/itimer.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/kernel/time/itimer.c
+++ b/kernel/time/itimer.c
@@ -138,8 +138,12 @@ static void set_cpu_itimer(struct task_s
u64 oval, nval, ointerval, ninterval;
struct cpu_itimer *it = &tsk->signal->it[clock_id];
- nval = timeval_to_ns(&value->it_value);
- ninterval = timeval_to_ns(&value->it_interval);
+ /*
+ * Use the to_ktime conversion because that clamps the maximum
+ * value to KTIME_MAX and avoid multiplication overflows.
+ */
+ nval = ktime_to_ns(timeval_to_ktime(value->it_value));
+ ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
spin_lock_irq(&tsk->sighand->siglock);
^ permalink raw reply [flat|nested] 5+ messages in thread
* [patch 2/2] posix-cpu-timers: Make timespec to nsec conversion safe
2017-06-20 15:37 [patch 0/2] timers: Prevent multiplication overflow in timespec/val conversions Thomas Gleixner
2017-06-20 15:37 ` [patch 1/2] itimer: Make timeval to nsec conversion range limited Thomas Gleixner
@ 2017-06-20 15:37 ` Thomas Gleixner
2017-06-20 19:40 ` [tip:timers/core] " tip-bot for Thomas Gleixner
1 sibling, 1 reply; 5+ messages in thread
From: Thomas Gleixner @ 2017-06-20 15:37 UTC (permalink / raw)
To: LKML; +Cc: John Stultz, Peter Zijlstra, Xishi Qiu
[-- Attachment #1: posix-cpu-timers--Make-timespec-to-nsec-conversion-safe.patch --]
[-- Type: text/plain, Size: 1199 bytes --]
The expiry time of a posix cpu timer is supplied through sys_timer_set()
via a struct timespec. The timespec is validated for correctness.
In the actual set timer implementation the timespec is converted to a
scalar nanoseconds value. If the tv_sec part of the time spec is large
enough the conversion to nanoseconds (sec * NSEC_PER_SEC) overflows 64bit.
Mitigate that by using the timespec_to_ktime() conversion function, which
checks the tv_sec part for a potential mult overflow and clamps the result
to KTIME_MAX, which is about 292 years.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/posix-cpu-timers.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -572,7 +572,11 @@ static int posix_cpu_timer_set(struct k_
WARN_ON_ONCE(p == NULL);
- new_expires = timespec64_to_ns(&new->it_value);
+ /*
+ * Use the to_ktime conversion because that clamps the maximum
+ * value to KTIME_MAX and avoid multiplication overflows.
+ */
+ new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value));
/*
* Protect against sighand release/switch in exit/exec and p->cpu_timers
^ permalink raw reply [flat|nested] 5+ messages in thread
* [tip:timers/core] itimer: Make timeval to nsec conversion range limited
2017-06-20 15:37 ` [patch 1/2] itimer: Make timeval to nsec conversion range limited Thomas Gleixner
@ 2017-06-20 19:39 ` tip-bot for Thomas Gleixner
0 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Thomas Gleixner @ 2017-06-20 19:39 UTC (permalink / raw)
To: linux-tip-commits
Cc: mingo, linux-kernel, hpa, peterz, qiuxishi, tglx, john.stultz
Commit-ID: 35eb7258c009dc478338e674a5a84d25d0929c56
Gitweb: http://git.kernel.org/tip/35eb7258c009dc478338e674a5a84d25d0929c56
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Tue, 20 Jun 2017 17:37:35 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 20 Jun 2017 21:33:56 +0200
itimer: Make timeval to nsec conversion range limited
The expiry time of a itimer is supplied through sys_setitimer() via a
struct timeval. The timeval is validated for correctness.
In the actual set timer implementation the timeval is converted to a
scalar nanoseconds value. If the tv_sec part of the time spec is large
enough the conversion to nanoseconds (sec * NSEC_PER_SEC) overflows 64bit.
Mitigate that by using the timeval_to_ktime() conversion function, which
checks the tv_sec part for a potential mult overflow and clamps the result
to KTIME_MAX, which is about 292 years.
Reported-by: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170620154113.505981643@linutronix.de
---
kernel/time/itimer.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c
index 9dd7ff5..2ef98a0 100644
--- a/kernel/time/itimer.c
+++ b/kernel/time/itimer.c
@@ -152,8 +152,12 @@ 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];
- nval = timeval_to_ns(&value->it_value);
- ninterval = timeval_to_ns(&value->it_interval);
+ /*
+ * Use the to_ktime conversion because that clamps the maximum
+ * value to KTIME_MAX and avoid multiplication overflows.
+ */
+ nval = ktime_to_ns(timeval_to_ktime(value->it_value));
+ ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
spin_lock_irq(&tsk->sighand->siglock);
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [tip:timers/core] posix-cpu-timers: Make timespec to nsec conversion safe
2017-06-20 15:37 ` [patch 2/2] posix-cpu-timers: Make timespec to nsec conversion safe Thomas Gleixner
@ 2017-06-20 19:40 ` tip-bot for Thomas Gleixner
0 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Thomas Gleixner @ 2017-06-20 19:40 UTC (permalink / raw)
To: linux-tip-commits
Cc: john.stultz, peterz, tglx, hpa, qiuxishi, linux-kernel, mingo
Commit-ID: 098b0e01a91c42aaaf0425605cd126b03fcb0bcf
Gitweb: http://git.kernel.org/tip/098b0e01a91c42aaaf0425605cd126b03fcb0bcf
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Tue, 20 Jun 2017 17:37:36 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 20 Jun 2017 21:33:56 +0200
posix-cpu-timers: Make timespec to nsec conversion safe
The expiry time of a posix cpu timer is supplied through sys_timer_set()
via a struct timespec. The timespec is validated for correctness.
In the actual set timer implementation the timespec is converted to a
scalar nanoseconds value. If the tv_sec part of the time spec is large
enough the conversion to nanoseconds (sec * NSEC_PER_SEC) overflows 64bit.
Mitigate that by using the timespec_to_ktime() conversion function, which
checks the tv_sec part for a potential mult overflow and clamps the result
to KTIME_MAX, which is about 292 years.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170620154113.588276707@linutronix.de
---
kernel/time/posix-cpu-timers.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 9df618e..60cb24a 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -580,7 +580,11 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
WARN_ON_ONCE(p == NULL);
- new_expires = timespec64_to_ns(&new->it_value);
+ /*
+ * Use the to_ktime conversion because that clamps the maximum
+ * value to KTIME_MAX and avoid multiplication overflows.
+ */
+ new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value));
/*
* Protect against sighand release/switch in exit/exec and p->cpu_timers
^ permalink raw reply related [flat|nested] 5+ messages in thread
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