From: HE WEI (ギカク) Date: Tue, 7 Jul 2026 09:48:28 +0000 (+0900) Subject: wifi: cfg80211: bound element ID read when checking non-inheritance X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cb8afea4655ff004fa7feee825d5c79783525383;p=thirdparty%2Fkernel%2Flinux.git wifi: cfg80211: bound element ID read when checking non-inheritance cfg80211_is_element_inherited() reads the first data octet of the candidate element (id = elem->data[0]) to look it up in an extension non-inheritance list. It does so after testing elem->id, but without verifying that the element actually has a data octet. A zero-length extension element (WLAN_EID_EXTENSION with length 0) therefore makes it read one octet past the end of the element. _ieee802_11_parse_elems_full() runs this check for every element of a frame once a non-inheritance context exists -- e.g. while parsing a per-STA profile of a Multi-Link element in a (re)association response, or a non-transmitted BSS profile -- so a crafted frame from an AP can trigger a one-octet slab-out-of-bounds read during element parsing: BUG: KASAN: slab-out-of-bounds in cfg80211_is_element_inherited Read of size 1 ... in net/wireless/scan.c Return early (treat the element as inherited) when an extension element carries no data, mirroring the existing handling of empty ID lists. The bug was found by fuzzing ieee802_11_parse_elems_full() under KASAN. Fixes: f7dacfb11475 ("cfg80211: support non-inheritance element") Signed-off-by: HE WEI (ギカク) Link: https://patch.msgid.link/20260707094828.16465-1-skyexpoc@gmail.com Signed-off-by: Johannes Berg --- diff --git a/net/wireless/scan.c b/net/wireless/scan.c index 5c97b5bd5d69..071083cc3367 100644 --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -205,7 +205,7 @@ bool cfg80211_is_element_inherited(const struct element *elem, return true; if (elem->id == WLAN_EID_EXTENSION) { - if (!ext_id_len) + if (!ext_id_len || !elem->datalen) return true; loop_len = ext_id_len; list = &non_inherit_elem->data[3 + id_len];