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authorWen Yang <wenyang@linux.alibaba.com>2020-01-20 18:05:23 +0800
committerThomas Gleixner <tglx@linutronix.de>2020-03-04 10:17:51 +0100
commit4cbbc3a0eeed675449b1a4d080008927121f3da3 (patch)
tree739aabe30a12d1aa42c056394faf89fb3b45444c /kernel/time
parentb95e31c07c5eb4f5c0769f12b38b0343d7961040 (diff)
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@linux.alibaba.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20200120100523.45656-1-wenyang@linux.alibaba.com
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/timekeeping.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index ca69290bee2a..4fc2af4367a7 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;
}