From cc0f9bb99735d2b68fac68f37b585d615728ce5b Mon Sep 17 00:00:00 2001 From: Ahmad Fatoum Date: Thu, 23 Mar 2023 11:37:35 +0100 Subject: [PATCH] net: dsa: realtek: fix out-of-bounds access MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ 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 Reviewed-by: Luiz Angelo Daros de Luca Reviewed-by: Alvin Šipraga Reviewed-by: Linus Walleij Signed-off-by: Ahmad Fatoum Link: https://lore.kernel.org/r/20230323103735.2331786-1-a.fatoum@pengutronix.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- 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 3e54fac5f902..5a8fe707ca25 100644 --- a/drivers/net/dsa/realtek/realtek-mdio.c +++ b/drivers/net/dsa/realtek/realtek-mdio.c @@ -21,6 +21,7 @@ #include #include +#include #include #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;