4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Carpenter <dan.carpenter@xxxxxxxxxx> commit 096cdc6f52225835ff503f987a0d68ef770bb78e upstream. We verify "u_cmd.outsize" and "u_cmd.insize" but we need to make sure that those values have not changed between the two copy_from_user() calls. Otherwise it could lead to a buffer overflow. Additionally, cros_ec_cmd_xfer() can set s_cmd->insize to a lower value. We should use the new smaller value so we don't copy too much data to the user. Reported-by: Pengfei Wang <wpengfeinudt@xxxxxxxxx> Fixes: a841178445bb ('mfd: cros_ec: Use a zero-length array for command data') Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Tested-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx> Signed-off-by: Olof Johansson <olof@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/platform/chrome/cros_ec_dev.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/drivers/platform/chrome/cros_ec_dev.c +++ b/drivers/platform/chrome/cros_ec_dev.c @@ -147,13 +147,19 @@ static long ec_device_ioctl_xcmd(struct goto exit; } + if (u_cmd.outsize != s_cmd->outsize || + u_cmd.insize != s_cmd->insize) { + ret = -EINVAL; + goto exit; + } + s_cmd->command += ec->cmd_offset; ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd); /* Only copy data to userland if data was received. */ if (ret < 0) goto exit; - if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize)) + if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize)) ret = -EFAULT; exit: kfree(s_cmd); -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html