On Fri, Oct 04, 2019 at 10:51:32AM +0100, Will Deacon wrote:
> Ensure the SSID element is bounds-checked prior to invoking memcpy()
> with its length field.
>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Reported-by: Nicolas Waisman <nico@xxxxxxxxxx>
> Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
-Kees
> ---
> net/wireless/wext-sme.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/net/wireless/wext-sme.c b/net/wireless/wext-sme.c
> index c67d7a82ab13..3fd2cc7fc36a 100644
> --- a/net/wireless/wext-sme.c
> +++ b/net/wireless/wext-sme.c
> @@ -201,6 +201,7 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev,
> struct iw_request_info *info,
> struct iw_point *data, char *ssid)
> {
> + int ret = 0;
> struct wireless_dev *wdev = dev->ieee80211_ptr;
>
> /* call only for station! */
> @@ -219,7 +220,10 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev,
> if (ie) {
> data->flags = 1;
> data->length = ie[1];
> - memcpy(ssid, ie + 2, data->length);
> + if (data->length > IW_ESSID_MAX_SIZE)
> + ret = -EINVAL;
> + else
> + memcpy(ssid, ie + 2, data->length);
> }
> rcu_read_unlock();
> } else if (wdev->wext.connect.ssid && wdev->wext.connect.ssid_len) {
> @@ -229,7 +233,7 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev,
> }
> wdev_unlock(wdev);
>
> - return 0;
> + return ret;
> }
>
> int cfg80211_mgd_wext_siwap(struct net_device *dev,
> --
> 2.23.0.581.g78d2f28ef7-goog
>
--
Kees Cook
