* [PATCH] hwmon (occ): Fix division by zero issue
@ 2019-07-11 2:44 Lei YU
2019-07-11 16:35 ` Guenter Roeck
0 siblings, 1 reply; 2+ messages in thread
From: Lei YU @ 2019-07-11 2:44 UTC (permalink / raw)
To: Jean Delvare, Guenter Roeck, Eddie James, Gustavo A . R . Silva,
Lei YU, linux-hwmon, linux-kernel
The code in occ_get_powr_avg() invokes div64_u64() without checking the
divisor. In case the divisor is zero, kernel gets an "Division by zero
in kernel" error.
Check the divisor and make it return 0 if the divisor is 0.
Signed-off-by: Lei YU <mine260309@gmail.com>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
---
drivers/hwmon/occ/common.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
index 13a6290..f02aa40 100644
--- a/drivers/hwmon/occ/common.c
+++ b/drivers/hwmon/occ/common.c
@@ -402,8 +402,10 @@ static ssize_t occ_show_power_1(struct device *dev,
static u64 occ_get_powr_avg(u64 *accum, u32 *samples)
{
- return div64_u64(get_unaligned_be64(accum) * 1000000ULL,
- get_unaligned_be32(samples));
+ u64 divisor = get_unaligned_be32(samples);
+
+ return (divisor == 0) ? 0 :
+ div64_u64(get_unaligned_be64(accum) * 1000000ULL, divisor);
}
static ssize_t occ_show_power_2(struct device *dev,
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] hwmon (occ): Fix division by zero issue
2019-07-11 2:44 [PATCH] hwmon (occ): Fix division by zero issue Lei YU
@ 2019-07-11 16:35 ` Guenter Roeck
0 siblings, 0 replies; 2+ messages in thread
From: Guenter Roeck @ 2019-07-11 16:35 UTC (permalink / raw)
To: Lei YU
Cc: Jean Delvare, Eddie James, Gustavo A . R . Silva, linux-hwmon,
linux-kernel
On Thu, Jul 11, 2019 at 10:44:48AM +0800, Lei YU wrote:
> The code in occ_get_powr_avg() invokes div64_u64() without checking the
> divisor. In case the divisor is zero, kernel gets an "Division by zero
> in kernel" error.
>
> Check the divisor and make it return 0 if the divisor is 0.
>
> Signed-off-by: Lei YU <mine260309@gmail.com>
> Reviewed-by: Eddie James <eajames@linux.ibm.com>
Applied.
Thanks,
Guenter
> ---
> drivers/hwmon/occ/common.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
> index 13a6290..f02aa40 100644
> --- a/drivers/hwmon/occ/common.c
> +++ b/drivers/hwmon/occ/common.c
> @@ -402,8 +402,10 @@ static ssize_t occ_show_power_1(struct device *dev,
>
> static u64 occ_get_powr_avg(u64 *accum, u32 *samples)
> {
> - return div64_u64(get_unaligned_be64(accum) * 1000000ULL,
> - get_unaligned_be32(samples));
> + u64 divisor = get_unaligned_be32(samples);
> +
> + return (divisor == 0) ? 0 :
> + div64_u64(get_unaligned_be64(accum) * 1000000ULL, divisor);
> }
>
> static ssize_t occ_show_power_2(struct device *dev,
^ permalink raw reply [flat|nested] 2+ messages in thread
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