[patch 1/2] itimer: Make timeval to nsec conversion range limited

[Thomas Gleixner]

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 
Signed-off-by: Thomas Gleixner 
---
 kernel/time/itimer.c |8 ++--
 1 file changed, 6 insertions(+), 2 deletions(-)


Signed-off-by: Thomas Gleixner 
---
 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 = >signal->it[clock_id];
 
-   nval = timeval_to_ns(>it_value);
-   ninterval = timeval_to_ns(>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(>sighand->siglock);
 

[patch 1/2] itimer: Make timeval to nsec conversion range limited

[Thomas Gleixner]

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 
Signed-off-by: Thomas Gleixner 
---
 kernel/time/itimer.c |8 ++--
 1 file changed, 6 insertions(+), 2 deletions(-)


Signed-off-by: Thomas Gleixner 
---
 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 = >signal->it[clock_id];
 
-   nval = timeval_to_ns(>it_value);
-   ninterval = timeval_to_ns(>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(>sighand->siglock);