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| author | Thomas Gleixner <tglx@linutronix.de> | 2018-07-02 10:34:29 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-07-02 12:33:26 +0300 |
| commit | 5f936e19cc0ef97dbe3a56e9498922ad5ba1edef (patch) | |
| tree | e090b44b1437642d9702c599576c0303c268ed8c | |
| parent | 78c9c4dfbf8c04883941445a195276bb4bb92c76 (diff) | |
| download | linux-5f936e19cc0ef97dbe3a56e9498922ad5ba1edef.tar.xz | |
alarmtimer: Prevent overflow for relative nanosleep
Air Icy reported:
UBSAN: Undefined behaviour in kernel/time/alarmtimer.c:811:7
signed integer overflow:
1529859276030040771 + 9223372036854775807 cannot be represented in type 'long long int'
Call Trace:
alarm_timer_nsleep+0x44c/0x510 kernel/time/alarmtimer.c:811
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1235 [inline]
__se_sys_clock_nanosleep kernel/time/posix-timers.c:1213 [inline]
__x64_sys_clock_nanosleep+0x326/0x4e0 kernel/time/posix-timers.c:1213
do_syscall_64+0xb8/0x3a0 arch/x86/entry/common.c:290
alarm_timer_nsleep() uses ktime_add() to add the current time and the
relative expiry value. ktime_add() has no sanity checks so the addition
can overflow when the relative timeout is large enough.
Use ktime_add_safe() which has the necessary sanity checks in place and
limits the result to the valid range.
Fixes: 9a7adcf5c6de ("timers: Posix interface for alarm-timers")
Reported-by: Team OWL337 <icytxw@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1807020926360.1595@nanos.tec.linutronix.de
| -rw-r--r-- | kernel/time/alarmtimer.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 78a3cc555823..fa5de5e8de61 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -808,7 +808,8 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags, /* Convert (if necessary) to absolute time */ if (flags != TIMER_ABSTIME) { ktime_t now = alarm_bases[type].gettime(); - exp = ktime_add(now, exp); + + exp = ktime_add_safe(now, exp); } ret = alarmtimer_do_nsleep(&alarm, exp, type); |