From: Kees Cook <keescook@chromium.org>
To: Will Deacon <will@kernel.org>
Cc: linux-wireless@vger.kernel.org, nico@semmle.com,
stable@vger.kernel.org, Johannes Berg <johannes@sipsolutions.net>
Subject: Re: [PATCH 1/2] mac80211: Reject malformed SSID elements
Date: Fri, 4 Oct 2019 08:55:50 -0700 [thread overview]
Message-ID: <201910040855.8E8B4D7A@keescook> (raw)
In-Reply-To: <20191004095132.15777-1-will@kernel.org>
On Fri, Oct 04, 2019 at 10:51:31AM +0100, Will Deacon wrote:
> Although this shouldn't occur in practice, it's a good idea to bounds
> check the length field of the SSID element prior to using it for things
> like allocations or memcpy operations.
>
> Cc: <stable@vger.kernel.org>
> Cc: Johannes Berg <johannes@sipsolutions.net>
> Cc: Kees Cook <keescook@chromium.org>
> Reported-by: Nicolas Waisman <nico@semmle.com>
> Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
> net/mac80211/mlme.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index 26a2f49208b6..54dd8849d1cc 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -2633,7 +2633,8 @@ struct sk_buff *ieee80211_ap_probereq_get(struct ieee80211_hw *hw,
>
> rcu_read_lock();
> ssid = ieee80211_bss_get_ie(cbss, WLAN_EID_SSID);
> - if (WARN_ON_ONCE(ssid == NULL))
> + if (WARN_ONCE(!ssid || ssid[1] > IEEE80211_MAX_SSID_LEN,
> + "invalid SSID element (len=%d)", ssid ? ssid[1] : -1))
> ssid_len = 0;
> else
> ssid_len = ssid[1];
> @@ -5233,7 +5234,7 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
>
> rcu_read_lock();
> ssidie = ieee80211_bss_get_ie(req->bss, WLAN_EID_SSID);
> - if (!ssidie) {
> + if (!ssidie || ssidie[1] > sizeof(assoc_data->ssid)) {
> rcu_read_unlock();
> kfree(assoc_data);
> return -EINVAL;
> --
> 2.23.0.581.g78d2f28ef7-goog
>
--
Kees Cook
prev parent reply other threads:[~2019-10-04 15:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-04 9:51 [PATCH 1/2] mac80211: Reject malformed SSID elements Will Deacon
2019-10-04 9:51 ` [PATCH 2/2] cfg80211: wext: " Will Deacon
2019-10-04 15:56 ` Kees Cook
2019-10-04 15:55 ` Kees Cook [this message]
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