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authorDan Carpenter <dan.carpenter@oracle.com>2016-06-21 16:58:46 +0300
committerOlof Johansson <olof@lixom.net>2016-07-05 14:01:52 -0700
commit096cdc6f52225835ff503f987a0d68ef770bb78e (patch)
tree7e123fe975c5578ff97ad21811f9e4500210fb0c
parent33688abb2802ff3a230bd2441f765477b94cc89e (diff)
downloadlinux-096cdc6f52225835ff503f987a0d68ef770bb78e.tar.gz
platform/chrome: cros_ec_dev - double fetch bug in ioctl
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@gmail.com> Fixes: a841178445bb ('mfd: cros_ec: Use a zero-length array for command data') Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Gwendal Grignou <gwendal@chromium.org> Cc: <stable@vger.kernel.org> # v4.2+ Signed-off-by: Olof Johansson <olof@lixom.net>
-rw-r--r--drivers/platform/chrome/cros_ec_dev.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/platform/chrome/cros_ec_dev.c b/drivers/platform/chrome/cros_ec_dev.c
index 6d8ee3b15872..8abd80dbcbed 100644
--- a/drivers/platform/chrome/cros_ec_dev.c
+++ b/drivers/platform/chrome/cros_ec_dev.c
@@ -151,13 +151,19 @@ static long ec_device_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
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);