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cfg80211: fix proto in ieee80211_data_to_8023 for frames without LLC header

Message ID 20160629083639.81261-1-nbd@nbd.name (mailing list archive)
State Accepted
Delegated to: Johannes Berg
Headers show

Commit Message

Felix Fietkau June 29, 2016, 8:36 a.m. UTC
The PDU length of incoming LLC frames is set to the total skb payload size
in __ieee80211_data_to_8023() of net/wireless/util.c which incorrectly
includes the length of the IEEE 802.11 header.

The resulting LLC frame header has a too large PDU length, causing the
llc_fixup_skb() function of net/llc/llc_input.c to reject the incoming
skb, effectively breaking STP.

Solve the problem by properly substracting the IEEE 802.11 frame header size
from the PDU length, allowing the LLC processor to pick up the incoming
control messages.

Special thanks to Gerry Rozema for tracking down the regression and proposing
a suitable patch.

Fixes: 2d1c304cb2d5 ("cfg80211: add function for 802.3 conversion with separate output buffer")
Cc: stable@vger.kernel.org
Reported-by: Gerry Rozema <gerryr@rozeware.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/wireless/util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 4e809e9..2443ee3 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -509,7 +509,7 @@  static int __ieee80211_data_to_8023(struct sk_buff *skb, struct ethhdr *ehdr,
 		 * replace EtherType */
 		hdrlen += ETH_ALEN + 2;
 	else
-		tmp.h_proto = htons(skb->len);
+		tmp.h_proto = htons(skb->len - hdrlen);
 
 	pskb_pull(skb, hdrlen);