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| author | Wen Yang <wenyang@linux.alibaba.com> | 2020-01-20 18:05:23 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-10-01 13:14:36 +0200 |
| commit | 627b771be7d7a36b1a62049912003736bc79edb4 (patch) | |
| tree | b3547a7b90cdef879190479e0d869c2e9f9ca005 | |
| parent | 1ee3da6b960b88bdfaa7a7efaf37ec3b0444c068 (diff) | |
timekeeping: Prevent 32bit truncation in scale64_check_overflow()
[ Upstream commit 4cbbc3a0eeed675449b1a4d080008927121f3da3 ]
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@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200120100523.45656-1-wenyang@linux.alibaba.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | kernel/time/timekeeping.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 81ee5b83c920..c66fd11d94bc 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1004,9 +1004,8 @@ 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; } |