mac80211: validate extended element ID is present

stable inclusion
from stable-v5.10.88
commit 7fd214fc7f2ee3a89f91e717e3cfad55f5a27045
bugzilla: 186058 https://gitee.com/openeuler/kernel/issues/I4QW6A

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7fd214fc7f2ee3a89f91e717e3cfad55f5a27045

--------------------------------

commit 768c0b19 upstream.

Before attempting to parse an extended element, verify that
the extended element ID is present.

Fixes: 41cbb0f5 ("mac80211: add support for HE")
Reported-by: syzbot+59bdff68edce82e393b6@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20211211201023.f30a1b128c07.I5cacc176da94ba316877c6e10fe3ceec8b4dbd7d@changeid
Cc: stable@vger.kernel.org
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/mac80211/util.c

@@ -950,7 +950,12 @@ static void ieee80211_parse_extension_element(u32 *crc,
 					      struct ieee802_11_elems *elems)
 {
 	const void *data = elem->data + 1;
-	u8 len = elem->datalen - 1;
+	u8 len;
+
+	if (!elem->datalen)
+		return;
+
+	len = elem->datalen - 1;
 
 	switch (elem->data[0]) {
 	case WLAN_EID_EXT_HE_MU_EDCA: