diff options
| author | Vegard Nossum <vegard.nossum@oracle.com> | 2016-08-13 01:37:04 +0200 |
|---|---|---|
| committer | John Stultz <john.stultz@linaro.org> | 2016-08-31 14:43:36 -0700 |
| commit | 979515c5645830465739254abc1b1648ada41518 (patch) | |
| tree | eb453dd43be0238e5a9cfca46eb82dd5b965e593 /include/linux/ktime.h | |
| parent | 469e857f374640f6164913835ce30d0736b40a60 (diff) | |
| download | linux-979515c5645830465739254abc1b1648ada41518.tar.gz linux-979515c5645830465739254abc1b1648ada41518.tar.bz2 linux-979515c5645830465739254abc1b1648ada41518.zip | |
time: Avoid undefined behaviour in ktime_add_safe()
I ran into this:
================================================================================
UBSAN: Undefined behaviour in kernel/time/hrtimer.c:310:16
signed integer overflow:
9223372036854775807 + 50000 cannot be represented in type 'long long int'
CPU: 2 PID: 4798 Comm: trinity-c2 Not tainted 4.8.0-rc1+ #91
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
0000000000000000 ffff88010ce6fb88 ffffffff82344740 0000000041b58ab3
ffffffff84f97a20 ffffffff82344694 ffff88010ce6fbb0 ffff88010ce6fb60
000000000000c350 ffff88010ce6f968 dffffc0000000000 ffffffff857bc320
Call Trace:
[<ffffffff82344740>] dump_stack+0xac/0xfc
[<ffffffff82344694>] ? _atomic_dec_and_lock+0xc4/0xc4
[<ffffffff8242df78>] ubsan_epilogue+0xd/0x8a
[<ffffffff8242e6b4>] handle_overflow+0x202/0x23d
[<ffffffff8242e4b2>] ? val_to_string.constprop.6+0x11e/0x11e
[<ffffffff8236df71>] ? timerqueue_add+0x151/0x410
[<ffffffff81485c48>] ? hrtimer_start_range_ns+0x3b8/0x1380
[<ffffffff81795631>] ? memset+0x31/0x40
[<ffffffff8242e6fd>] __ubsan_handle_add_overflow+0xe/0x10
[<ffffffff81488ac9>] hrtimer_nanosleep+0x5d9/0x790
[<ffffffff814884f0>] ? hrtimer_init_sleeper+0x80/0x80
[<ffffffff813a9ffb>] ? __might_sleep+0x5b/0x260
[<ffffffff8148be10>] common_nsleep+0x20/0x30
[<ffffffff814906c7>] SyS_clock_nanosleep+0x197/0x210
[<ffffffff81490530>] ? SyS_clock_getres+0x150/0x150
[<ffffffff823c7113>] ? __this_cpu_preempt_check+0x13/0x20
[<ffffffff8162ef60>] ? __context_tracking_exit.part.3+0x30/0x1b0
[<ffffffff81490530>] ? SyS_clock_getres+0x150/0x150
[<ffffffff81007bd3>] do_syscall_64+0x1b3/0x4b0
[<ffffffff845f85aa>] entry_SYSCALL64_slow_path+0x25/0x25
================================================================================
Add a new ktime_add_unsafe() helper which doesn't check for overflow, but
doesn't throw a UBSAN warning when it does overflow either.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'include/linux/ktime.h')
| -rw-r--r-- | include/linux/ktime.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/ktime.h b/include/linux/ktime.h index 2b6a204bd8d4..3ffc69ebe967 100644 --- a/include/linux/ktime.h +++ b/include/linux/ktime.h @@ -64,6 +64,13 @@ static inline ktime_t ktime_set(const s64 secs, const unsigned long nsecs) ({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; }) /* + * Same as ktime_add(), but avoids undefined behaviour on overflow; however, + * this means that you must check the result for overflow yourself. + */ +#define ktime_add_unsafe(lhs, rhs) \ + ({ (ktime_t){ .tv64 = (u64) (lhs).tv64 + (rhs).tv64 }; }) + +/* * Add a ktime_t variable and a scalar nanosecond value. * res = kt + nsval: */ |