Re: [PATCH] hwmon (occ): Fix potential integer overflow

From: Eddie James
Date: Mon Jan 07 2019 - 13:43:41 EST




On 01/07/2019 12:34 PM, Gustavo A. R. Silva wrote:
Cast get_unaligned_be32(...) to u64 in order to give the compiler
complete information about the proper arithmetic to use and avoid
a potential integer overflow.

Notice that such function call is used in contexts that expect
expressions of type u64 (64 bits, unsigned); and the following
expressions are currently being evaluated using 32-bit
arithmetic:

val = get_unaligned_be32(&power->update_tag) *
occ->powr_sample_time_us;

val = get_unaligned_be32(&power->vdn.update_tag) *
occ->powr_sample_time_us;

Thanks,

Reviewed-by: Eddie James <eajames@xxxxxxxxxxxxx>


Addresses-Coverity-ID: 1442357 ("Unintentional integer overflow")
Addresses-Coverity-ID: 1442476 ("Unintentional integer overflow")
Addresses-Coverity-ID: 1442508 ("Unintentional integer overflow")
Fixes: ff692d80b2e2 ("hwmon (occ): Add sensor types and versions")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
drivers/hwmon/occ/common.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
index 423903f87955..391118c8aae8 100644
--- a/drivers/hwmon/occ/common.c
+++ b/drivers/hwmon/occ/common.c
@@ -380,8 +380,8 @@ static ssize_t occ_show_power_1(struct device *dev,
val *= 1000000ULL;
break;
case 2:
- val = get_unaligned_be32(&power->update_tag) *
- occ->powr_sample_time_us;
+ val = (u64)get_unaligned_be32(&power->update_tag) *
+ occ->powr_sample_time_us;
break;
case 3:
val = get_unaligned_be16(&power->value) * 1000000ULL;
@@ -425,8 +425,8 @@ static ssize_t occ_show_power_2(struct device *dev,
&power->update_tag);
break;
case 2:
- val = get_unaligned_be32(&power->update_tag) *
- occ->powr_sample_time_us;
+ val = (u64)get_unaligned_be32(&power->update_tag) *
+ occ->powr_sample_time_us;
break;
case 3:
val = get_unaligned_be16(&power->value) * 1000000ULL;
@@ -463,8 +463,8 @@ static ssize_t occ_show_power_a0(struct device *dev,
&power->system.update_tag);
break;
case 2:
- val = get_unaligned_be32(&power->system.update_tag) *
- occ->powr_sample_time_us;
+ val = (u64)get_unaligned_be32(&power->system.update_tag) *
+ occ->powr_sample_time_us;
break;
case 3:
val = get_unaligned_be16(&power->system.value) * 1000000ULL;
@@ -477,8 +477,8 @@ static ssize_t occ_show_power_a0(struct device *dev,
&power->proc.update_tag);
break;
case 6:
- val = get_unaligned_be32(&power->proc.update_tag) *
- occ->powr_sample_time_us;
+ val = (u64)get_unaligned_be32(&power->proc.update_tag) *
+ occ->powr_sample_time_us;
break;
case 7:
val = get_unaligned_be16(&power->proc.value) * 1000000ULL;
@@ -491,8 +491,8 @@ static ssize_t occ_show_power_a0(struct device *dev,
&power->vdd.update_tag);
break;
case 10:
- val = get_unaligned_be32(&power->vdd.update_tag) *
- occ->powr_sample_time_us;
+ val = (u64)get_unaligned_be32(&power->vdd.update_tag) *
+ occ->powr_sample_time_us;
break;
case 11:
val = get_unaligned_be16(&power->vdd.value) * 1000000ULL;
@@ -505,8 +505,8 @@ static ssize_t occ_show_power_a0(struct device *dev,
&power->vdn.update_tag);
break;
case 14:
- val = get_unaligned_be32(&power->vdn.update_tag) *
- occ->powr_sample_time_us;
+ val = (u64)get_unaligned_be32(&power->vdn.update_tag) *
+ occ->powr_sample_time_us;
break;
case 15:
val = get_unaligned_be16(&power->vdn.value) * 1000000ULL;