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| Started by | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| First post | 2017-06-20 17:50 +0200 |
| Last post | 2017-06-20 21:50 +0200 |
| Articles | 5 — 2 participants |
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[patch 0/2] timers: Prevent multiplication overflow in timespec/val conversions Thomas Gleixner <tglx@linutronix.de> - 2017-06-20 17:50 +0200
[patch 1/2] itimer: Make timeval to nsec conversion range limited Thomas Gleixner <tglx@linutronix.de> - 2017-06-20 17:50 +0200
[tip:timers/core] itimer: Make timeval to nsec conversion range limited tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-06-20 21:50 +0200
[patch 2/2] posix-cpu-timers: Make timespec to nsec conversion safe Thomas Gleixner <tglx@linutronix.de> - 2017-06-20 17:50 +0200
[tip:timers/core] posix-cpu-timers: Make timespec to nsec conversion safe tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-06-20 21:50 +0200
| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2017-06-20 17:50 +0200 |
| Subject | [patch 0/2] timers: Prevent multiplication overflow in timespec/val conversions |
| Message-ID | <tUtzH-238-7@gated-at.bofh.it> |
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
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| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2017-06-20 17:50 +0200 |
| Subject | [patch 1/2] itimer: Make timeval to nsec conversion range limited |
| Message-ID | <tUtzI-238-23@gated-at.bofh.it> |
| In reply to | #1670884 |
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);
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| From | tip-bot for Thomas Gleixner <tipbot@zytor.com> |
|---|---|
| Date | 2017-06-20 21:50 +0200 |
| Subject | [tip:timers/core] itimer: Make timeval to nsec conversion range limited |
| Message-ID | <tUxjX-4nI-5@gated-at.bofh.it> |
| In reply to | #1670890 |
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);
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| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2017-06-20 17:50 +0200 |
| Subject | [patch 2/2] posix-cpu-timers: Make timespec to nsec conversion safe |
| Message-ID | <tUtzJ-238-35@gated-at.bofh.it> |
| In reply to | #1670884 |
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
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| From | tip-bot for Thomas Gleixner <tipbot@zytor.com> |
|---|---|
| Date | 2017-06-20 21:50 +0200 |
| Subject | [tip:timers/core] posix-cpu-timers: Make timespec to nsec conversion safe |
| Message-ID | <tUxjY-4nI-23@gated-at.bofh.it> |
| In reply to | #1670894 |
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
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