platform/chrome: cros_ec_chardev: fix kernel data leak from ioctl

[ Upstream commit b20cf3f89c56b5f6a38b7f76a8128bf9f291bbd3 ]

It is possible to peep kernel page's data by providing larger `insize`
in struct cros_ec_command[1] when invoking EC host commands.

Fix it by using zeroed memory.

[1]: https://elixir.bootlin.com/linux/v6.2/source/include/linux/platform_data/cros_ec_proto.h#L74

Fixes: 8c93ae858843 ("mfd / platform: cros_ec: Miscellaneous character device to talk with the EC")
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20230324010658.1082361-1-tzungbi@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/platform/chrome/cros_ec_chardev.c b/drivers/platform/chrome/cros_ec_chardev.c
index 1f5f4a46ab748b7c3284a69a11618ed5aa38da09..4791b62c2923f7880cdaa9357b89e18072c3ee6b 100644 (file)
--- a/drivers/platform/chrome/cros_ec_chardev.c
+++ b/drivers/platform/chrome/cros_ec_chardev.c
@@ -285,7 +285,7 @@ static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
            u_cmd.insize > EC_MAX_MSG_BYTES)
                return -EINVAL;
 
-       s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
+       s_cmd = kzalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
                        GFP_KERNEL);
        if (!s_cmd)
                return -ENOMEM;