From: tq17373059@buaa.edu.cn
To: lars@metafoo.de, Michael.Hennerich@analog.com, jic23@kernel.org
Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
baijiaju@tsinghua.edu.cn, Qi Teng <tq17373059@buaa.edu.cn>,
TOTE Robot <oslab@tsinghua.edu.cn>
Subject: [PATCH] iio: adf4350: fix a possible divided-by-zero bug in adf4350_set_freq()
Date: Fri, 21 May 2021 14:19:53 +0800 [thread overview]
Message-ID: <20210521061953.35873-1-tq17373059@buaa.edu.cn> (raw)
From: Qi Teng <tq17373059@buaa.edu.cn>
The variable st->r1_mod is checked in:
if (st->r0_fract && st->r1_mod)
This indicates that st->r1_mod can be zero. Its value is the same as
that in:
st->r0_fract = do_div(tmp, st->r1_mod);
However, st->r1_mod performs as a divisor in this statement, which
implies a possible divided-by-zero bug.
To fix this possible bug, st->r1_mod is checked before the division
operation. If it is zero, st->r0_fract is set to zero instead of
do_div(tmp, st->r1_mod).
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Qi Teng <tq17373059@buaa.edu.cn>
---
drivers/iio/frequency/adf4350.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/iio/frequency/adf4350.c b/drivers/iio/frequency/adf4350.c
index 99c6f260cc21..1462a6a5bc6d 100644
--- a/drivers/iio/frequency/adf4350.c
+++ b/drivers/iio/frequency/adf4350.c
@@ -182,10 +182,7 @@ static int adf4350_set_freq(struct adf4350_state *st, unsigned long long freq)
tmp = freq * (u64)st->r1_mod + (st->fpfd >> 1);
do_div(tmp, st->fpfd); /* Div round closest (n + d/2)/d */
- if (st->r1_mod)
- st->r0_fract = do_div(tmp, st->r1_mod);
- else
- st->r0_fract = 0;
+ st->r0_fract = do_div(tmp, st->r1_mod);
st->r0_int = tmp;
} while (mdiv > st->r0_int);
--
2.25.1
next reply other threads:[~2021-05-21 6:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-21 6:19 tq17373059 [this message]
2021-05-21 17:25 ` [PATCH] iio: adf4350: fix a possible divided-by-zero bug in adf4350_set_freq() Jonathan Cameron
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