time: Improve sanity checking of timekeeping inputs
authorJohn Stultz <john.stultz@linaro.org>
Tue, 11 Sep 2012 19:04:17 +0000 (15:04 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 2 Oct 2012 17:30:36 +0000 (10:30 -0700)
commit8e878154f5658ba93cf9bb2b491a930ec195de3d
tree7c90f9cafce87cdf0b5629933a35144ee3d11d44
parent504471eb5044e4a1dd10950d1a3efab39ba2083a
time: Improve sanity checking of timekeeping inputs

commit 4e8b14526ca7fb046a81c94002c1c43b6fdf0e9b upstream.

Unexpected behavior could occur if the time is set to a value large
enough to overflow a 64bit ktime_t (which is something larger then the
year 2262).

Also unexpected behavior could occur if large negative offsets are
injected via adjtimex.

So this patch improves the sanity check timekeeping inputs by
improving the timespec_valid() check, and then makes better use of
timespec_valid() to make sure we don't set the time to an invalid
negative value or one that overflows ktime_t.

Note: This does not protect from setting the time close to overflowing
ktime_t and then letting natural accumulation cause the overflow.

Reported-by: CAI Qian <caiqian@redhat.com>
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Zhouping Liu <zliu@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1344454580-17031-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
include/linux/ktime.h
include/linux/time.h
kernel/time/timekeeping.c