[lvc-project] [PATCH net v2] net: phy: mscc-miim: Validate bus frequency obtained from Device Tree

[Aleksandr Mishin]

In mscc_miim_clk_set() miim->bus_freq is taken from Device Tree and can
contain any value in case of any error or broken DT. A value of 2147483648
multiplied by 2 will result in an overflow and division by 0.

Add bus frequency value check to avoid overflow.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: bb2a1934ca01 ("net: phy: mscc-miim: add support to set MDIO bus frequency")
Suggested-by: Michael Walle <michael at walle.cc>
Signed-off-by: Aleksandr Mishin <amishin at t-argos.ru>
---
v1->v2: Detect overflow event instead of using magic numbers as suggested by Michael

 drivers/net/mdio/mdio-mscc-miim.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/mdio/mdio-mscc-miim.c b/drivers/net/mdio/mdio-mscc-miim.c
index c29377c85307..b344d0b03d8e 100644
--- a/drivers/net/mdio/mdio-mscc-miim.c
+++ b/drivers/net/mdio/mdio-mscc-miim.c
@@ -254,6 +254,11 @@ static int mscc_miim_clk_set(struct mii_bus *bus)
 	if (!miim->bus_freq)
 		return 0;
 
+	if (2 * miim->bus_freq == 0) {
+		dev_err(&bus->dev, "Incorrect bus frequency\n");
+		return -EINVAL;
+	}
+
 	rate = clk_get_rate(miim->clk);
 
 	div = DIV_ROUND_UP(rate, 2 * miim->bus_freq) - 1;
-- 
2.30.2