[PATCH AUTOSEL 6.5 37/45] wifi: mac80211_hwsim: drop short frames

[Sasha Levin]

From: Johannes Berg <johannes.berg@xxxxxxxxx>

[ Upstream commit fba360a047d5eeeb9d4b7c3a9b1c8308980ce9a6 ]

While technically some control frames like ACK are shorter and
end after Address 1, such frames shouldn't be forwarded through
wmediumd or similar userspace, so require the full 3-address
header to avoid accessing invalid memory if shorter frames are
passed in.

Reported-by: syzbot+b2645b5bf1512b81fa22@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Jeff Johnson <quic_jjohnson@xxxxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/wireless/virtual/mac80211_hwsim.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/virtual/mac80211_hwsim.c b/drivers/net/wireless/virtual/mac80211_hwsim.c
index f446fd0e8cd0d..dd516cec41973 100644
--- a/drivers/net/wireless/virtual/mac80211_hwsim.c
+++ b/drivers/net/wireless/virtual/mac80211_hwsim.c
@@ -5626,14 +5626,15 @@ static int hwsim_cloned_frame_received_nl(struct sk_buff *skb_2,
 	frame_data_len = nla_len(info->attrs[HWSIM_ATTR_FRAME]);
 	frame_data = (void *)nla_data(info->attrs[HWSIM_ATTR_FRAME]);
 
+	if (frame_data_len < sizeof(struct ieee80211_hdr_3addr) ||
+	    frame_data_len > IEEE80211_MAX_DATA_LEN)
+		goto err;
+
 	/* Allocate new skb here */
 	skb = alloc_skb(frame_data_len, GFP_KERNEL);
 	if (skb == NULL)
 		goto err;
 
-	if (frame_data_len > IEEE80211_MAX_DATA_LEN)
-		goto err;
-
 	/* Copy the data */
 	skb_put_data(skb, frame_data, frame_data_len);
 
-- 
2.40.1