From: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
[ Upstream commit b93eb564869321d0dffaf23fcc5c88112ed62466 ]
The probe function sets priv->chip_data to (void *)priv + sizeof(*priv)
with the expectation that priv has enough trailing space.
However, only realtek-smi actually allocated this chip_data space.
Do likewise in realtek-mdio to fix out-of-bounds accesses.
These accesses likely went unnoticed so far, because of an (unused)
buf[4096] member in struct realtek_priv, which caused kmalloc to
round up the allocated buffer to a big enough size, so nothing of
value was overwritten. With a different allocator (like in the barebox
bootloader port of the driver) or with KASAN, the memory corruption
becomes quickly apparent.
Fixes: aac94001067d ("net: dsa: realtek: add new mdio interface for drivers")
Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Reviewed-by: Luiz Angelo Daros de Luca <luizluca@xxxxxxxxx>
Reviewed-by: Alvin Šipraga <alsi@xxxxxxxxxxxxxxx>
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230323103735.2331786-1-a.fatoum@xxxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/net/dsa/realtek/realtek-mdio.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/net/dsa/realtek/realtek-mdio.c b/drivers/net/dsa/realtek/realtek-mdio.c
index 3e54fac5f9027..5a8fe707ca25e 100644
--- a/drivers/net/dsa/realtek/realtek-mdio.c
+++ b/drivers/net/dsa/realtek/realtek-mdio.c
@@ -21,6 +21,7 @@
#include <linux/module.h>
#include <linux/of_device.h>
+#include <linux/overflow.h>
#include <linux/regmap.h>
#include "realtek.h"
@@ -152,7 +153,9 @@ static int realtek_mdio_probe(struct mdio_device *mdiodev)
if (!var)
return -EINVAL;
- priv = devm_kzalloc(&mdiodev->dev, sizeof(*priv), GFP_KERNEL);
+ priv = devm_kzalloc(&mdiodev->dev,
+ size_add(sizeof(*priv), var->chip_data_sz),
+ GFP_KERNEL);
if (!priv)
return -ENOMEM;
--
2.39.2
