[PATCH] OPP: of: Fix potential multiplication overflow when calculating freq

[PATCH] OPP: of: Fix potential multiplication overflow when calculating freq

[Colin Ian King]

The multiplication be32_to_cpup(val++) * 1000 is performed using 32 bit
unsigned integers and hence uses a 32 bit multiplication; this will
overflow if be32_to_cpup(val++) is greater than 4294967 (which is
very unlikely at present). The result is assigned to an unsigned long
(which is a 64 bit value on 64 bit systems), so fix this potential
overflow by casting the first operand of the multiplication to
an unsigned int.

Fixes: b496dfbc94ab ("PM / OPP: Initialize OPP table from device tree")

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
---
 drivers/opp/of.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index c02e20632fa6..9c4fd1f0e944 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -1039,7 +1039,7 @@ static int _of_add_opp_table_v1(struct device *dev, struct opp_table *opp_table)
 
 	val = prop->value;
 	while (nr) {
-		unsigned long freq = be32_to_cpup(val++) * 1000;
+		unsigned long freq = (unsigned long)be32_to_cpup(val++) * 1000;
 		unsigned long volt = be32_to_cpup(val++);
 		struct dev_pm_opp_data data = {
 			.freq = freq,
-- 
2.55.0

Re: [PATCH] OPP: of: Fix potential multiplication overflow when calculating freq

[Viresh Kumar]

On 26-08-26, 14:19, Colin Ian King wrote:
> The multiplication be32_to_cpup(val++) * 1000 is performed using 32 bit
> unsigned integers and hence uses a 32 bit multiplication; this will
> overflow if be32_to_cpup(val++) is greater than 4294967 (which is
> very unlikely at present). The result is assigned to an unsigned long
> (which is a 64 bit value on 64 bit systems), so fix this potential
> overflow by casting the first operand of the multiplication to
> an unsigned int.
> 
> Fixes: b496dfbc94ab ("PM / OPP: Initialize OPP table from device tree")
> 
> Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
> ---
>  drivers/opp/of.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied. Thanks.

-- 
viresh