[PATCH 5.18 431/879] mt76: mt7915: fix unbounded shift in mt7915_mcu_beacon_mbss

Greg Kroah-Hartman
2022-06-08T00:15:07Z

From: Lorenzo Bianconi <lorenzo@kernel.org>

[ Upstream commit aa796f12091aa4758366f5171fd9cba2ff574ba3 ]

Fix the following smatch static checker warning:
drivers/net/wireless/mediatek/mt76/mt7915/mcu.c:1872 mt7915_mcu_beacon_mbss()
error: undefined (user controlled) shift '(((1))) << (data[2])'

Rely on mac80211 definitions for ieee80211_bssid_index subelement.

Fixes: 6b7f9aff7c67 ("mt76: mt7915: introduce 802.11ax multi-bss support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../net/wireless/mediatek/mt76/mt7915/mcu.c | 20 ++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
index e7a6f80e7755..736c9c342baa 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
@@ -1854,7 +1854,8 @@ mt7915_mcu_beacon_mbss(struct sk_buff *rskb, struct sk_buff *skb,
continue;

for_each_element(sub_elem, elem->data + 1, elem->datalen - 1) {
- const u8 *data;
+ const struct ieee80211_bssid_index *idx;
+ const u8 *idx_ie;

if (sub_elem->id || sub_elem->datalen < 4)
continue; /* not a valid BSS profile */
@@ -1862,14 +1863,19 @@ mt7915_mcu_beacon_mbss(struct sk_buff *rskb, struct sk_buff *skb,
/* Find WLAN_EID_MULTI_BSSID_IDX
* in the merged nontransmitted profile
*/
- data = cfg80211_find_ie(WLAN_EID_MULTI_BSSID_IDX,
- sub_elem->data,
- sub_elem->datalen);
- if (!data || data[1] < 1 || !data[2])
+ idx_ie = cfg80211_find_ie(WLAN_EID_MULTI_BSSID_IDX,
+ sub_elem->data,
+ sub_elem->datalen);
+ if (!idx_ie || idx_ie[1] < sizeof(*idx))
continue;

- mbss->offset[data[2]] = cpu_to_le16(data - skb->data);
- mbss->bitmap |= cpu_to_le32(BIT(data[2]));
+ idx = (void *)(idx_ie + 2);
+ if (!idx->bssid_index || idx->bssid_index > 31)
+ continue;
+
+ mbss->offset[idx->bssid_index] =
+ cpu_to_le16(idx_ie - skb->data);
+ mbss->bitmap |= cpu_to_le32(BIT(idx->bssid_index));
}
}
}
--
2.35.1