The following commit has been merged into the timers/core branch of tip: Commit-ID: 4cbbc3a0eeed675449b1a4d080008927121f3da3 Gitweb: https://git.kernel.org/tip/4cbbc3a0eeed675449b1a4d080008927121f3da3 Author: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx> AuthorDate: Mon, 20 Jan 2020 18:05:23 +08:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Wed, 04 Mar 2020 10:17:51 +01:00 timekeeping: Prevent 32bit truncation in scale64_check_overflow() While unlikely the divisor in scale64_check_overflow() could be >= 32bit in scale64_check_overflow(). do_div() truncates the divisor to 32bit at least on 32bit platforms. Use div64_u64() instead to avoid the truncation to 32-bit. [ tglx: Massaged changelog ] Signed-off-by: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20200120100523.45656-1-wenyang@xxxxxxxxxxxxxxxxx --- kernel/time/timekeeping.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index ca69290..4fc2af4 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1005,9 +1005,8 @@ static int scale64_check_overflow(u64 mult, u64 div, u64 *base) ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem))) return -EOVERFLOW; tmp *= mult; - rem *= mult; - do_div(rem, div); + rem = div64_u64(rem * mult, div); *base = tmp + rem; return 0; }
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