[PATCH 5.4 091/255] platform/chrome: fix memory corruption in ioctl

[Greg Kroah-Hartman]

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ Upstream commit 8a07b45fd3c2dda24fad43639be5335a4595196a ]

If "s_mem.bytes" is larger than the buffer size it leads to memory
corruption.

Fixes: eda2e30c6684 ("mfd / platform: cros_ec: Miscellaneous character device to talk with the EC")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
Signed-off-by: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
Link: https://lore.kernel.org/r/Yv8dpCFZJdbUT5ye@kili
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/platform/chrome/cros_ec_chardev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_chardev.c b/drivers/platform/chrome/cros_ec_chardev.c
index 74ded441bb50..1f5f4a46ab74 100644
--- a/drivers/platform/chrome/cros_ec_chardev.c
+++ b/drivers/platform/chrome/cros_ec_chardev.c
@@ -328,6 +328,9 @@ static long cros_ec_chardev_ioctl_readmem(struct cros_ec_dev *ec,
 	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
 		return -EFAULT;
 
+	if (s_mem.bytes > sizeof(s_mem.buffer))
+		return -EINVAL;
+
 	num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
 				  s_mem.buffer);
 	if (num <= 0)
-- 
2.35.1