| Message ID | 20230323103735.2331786-1-a.fatoum@pengutronix.de (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | b93eb564869321d0dffaf23fcc5c88112ed62466 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] net: dsa: realtek: fix out-of-bounds access | expand |
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Thu, 23 Mar 2023 11:37:35 +0100 you wrote: > 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. > > [...] Here is the summary with links: - [net,v2] net: dsa: realtek: fix out-of-bounds access https://git.kernel.org/netdev/net/c/b93eb5648693 You are awesome, thank you!
diff --git a/drivers/net/dsa/realtek/realtek-mdio.c b/drivers/net/dsa/realtek/realtek-mdio.c index 7134886fe78d..1691faf77f00 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;
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@gmail.com> Reviewed-by: Luiz Angelo Daros de Luca <luizluca@gmail.com> Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de> --- v1 -> v2: - drop v1's patch 2/2, which appears to have no functional effect (Jakub) - extend commit message with probable reason why this long standing bug did not pop up so far in Linux (Prompted by Linus' question) - use saturating size_add instead of wrap-around addition (Jakub) - added reviewer R-b's --- drivers/net/dsa/realtek/realtek-mdio.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)