wifi: cfg80211: fix u8 overflow in cfg80211_update_notlisted_nontrans()

commit aebe9f4639b13a1f4e9a6b42cdd2e38c617b442d upstream.

In the copy code of the elements, we do the following calculation
to reach the end of the MBSSID element:

	/* copy the IEs after MBSSID */
	cpy_len = mbssid[1] + 2;

This looks fine, however, cpy_len is a u8, the same as mbssid[1],
so the addition of two can overflow. In this case the subsequent
memcpy() will overflow the allocated buffer, since it copies 256
bytes too much due to the way the allocation and memcpy() sizes
are calculated.

Fix this by using size_t for the cpy_len variable.

This fixes CVE-2022-41674.

Reported-by: Soenke Huster <shuster@seemoo.tu-darmstadt.de>
Tested-by: Soenke Huster <shuster@seemoo.tu-darmstadt.de>
Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 0134e5d5c81a4f9297fa7d8d5fdc45f0e6ae21eb..f59bfc09ca60f9666f0a58e74689423b696794dd 100644 (file)
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2279,7 +2279,7 @@ cfg80211_update_notlisted_nontrans(struct wiphy *wiphy,
        size_t new_ie_len;
        struct cfg80211_bss_ies *new_ies;
        const struct cfg80211_bss_ies *old;
-       u8 cpy_len;
+       size_t cpy_len;
 
        lockdep_assert_held(&wiphy_to_rdev(wiphy)->bss_lock);