The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a1d5ff5651ea592c67054233b14b30bf4452999c Mon Sep 17 00:00:00 2001

From: Mathy Vanhoef Mathy.Vanhoef@kuleuven.be Date: Tue, 11 May 2021 20:02:44 +0200 Subject: [PATCH] mac80211: properly handle A-MSDUs that start with an RFC 1042 header

Properly parse A-MSDUs whose first 6 bytes happen to equal a rfc1042 header. This can occur in practice when the destination MAC address equals AA:AA:03:00:00:00. More importantly, this simplifies the next patch to mitigate A-MSDU injection attacks.

Cc: stable@vger.kernel.org Signed-off-by: Mathy Vanhoef Mathy.Vanhoef@kuleuven.be Link: https://lore.kernel.org/r/20210511200110.0b2b886492f0.I23dd5d685fe16d3b0ec81... Signed-off-by: Johannes Berg johannes.berg@intel.com

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h index 5224f885a99a..58c2cd417e89 100644 --- a/include/net/cfg80211.h +++ b/include/net/cfg80211.h @@ -5760,7 +5760,7 @@ unsigned int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr); */ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr, const u8 *addr, enum nl80211_iftype iftype, - u8 data_offset); + u8 data_offset, bool is_amsdu);

/** * ieee80211_data_to_8023 - convert an 802.11 data frame to 802.3 @@ -5772,7 +5772,7 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr, static inline int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr, enum nl80211_iftype iftype) { - return ieee80211_data_to_8023_exthdr(skb, NULL, addr, iftype, 0); + return ieee80211_data_to_8023_exthdr(skb, NULL, addr, iftype, 0, false); }

/** diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index 531232b91bc4..f14d32a5001d 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -2682,7 +2682,7 @@ __ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx, u8 data_offset) if (ieee80211_data_to_8023_exthdr(skb, &ethhdr, rx->sdata->vif.addr, rx->sdata->vif.type, - data_offset)) + data_offset, true)) return RX_DROP_UNUSABLE;

ieee80211_amsdu_to_8023s(skb, &frame_list, dev->dev_addr, diff --git a/net/wireless/util.c b/net/wireless/util.c index 382c5262d997..39966a873e40 100644 --- a/net/wireless/util.c +++ b/net/wireless/util.c @@ -542,7 +542,7 @@ EXPORT_SYMBOL(ieee80211_get_mesh_hdrlen);

int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr, const u8 *addr, enum nl80211_iftype iftype, - u8 data_offset) + u8 data_offset, bool is_amsdu) { struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; struct { @@ -629,7 +629,7 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr, skb_copy_bits(skb, hdrlen, &payload, sizeof(payload)); tmp.h_proto = payload.proto;

- if (likely((ether_addr_equal(payload.hdr, rfc1042_header) && + if (likely((!is_amsdu && ether_addr_equal(payload.hdr, rfc1042_header) && tmp.h_proto != htons(ETH_P_AARP) && tmp.h_proto != htons(ETH_P_IPX)) || ether_addr_equal(payload.hdr, bridge_tunnel_header)))