lkml.org 
[lkml]   [2018]   [Oct]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.14 041/137] alarmtimer: Prevent overflow for relative nanosleep
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Thomas Gleixner <tglx@linutronix.de>

    [ Upstream commit 5f936e19cc0ef97dbe3a56e9498922ad5ba1edef ]

    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
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    kernel/time/alarmtimer.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/kernel/time/alarmtimer.c
    +++ b/kernel/time/alarmtimer.c
    @@ -808,7 +808,8 @@ static int alarm_timer_nsleep(const cloc
    /* 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);

    \
     
     \ /
      Last update: 2018-10-02 15:54    [W:4.055 / U:0.072 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site