| Message ID | 1392987561-14347-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 79cfca3..df9e376 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -909,7 +909,7 @@ static int ieee80211_fragment(struct ieee80211_tx_data *tx, } /* adjust first fragment's length */ - skb->len = hdrlen + per_fragm; + skb_trim(skb, hdrlen + per_fragm); return 0; }
This is a note to let you know that I have just added a patch titled mac80211: fix fragmentation code, particularly for encryption to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From cb146c0c0ef6df383efbea9f95795e93f38873f5 Mon Sep 17 00:00:00 2001 From: Johannes Berg <johannes.berg@intel.com> Date: Sat, 1 Feb 2014 00:16:23 +0100 Subject: mac80211: fix fragmentation code, particularly for encryption commit 338f977f4eb441e69bb9a46eaa0ac715c931a67f upstream. The "new" fragmentation code (since my rewrite almost 5 years ago) erroneously sets skb->len rather than using skb_trim() to adjust the length of the first fragment after copying out all the others. This leaves the skb tail pointer pointing to after where the data originally ended, and thus causes the encryption MIC to be written at that point, rather than where it belongs: immediately after the data. The impact of this is that if software encryption is done, then a) encryption doesn't work for the first fragment, the connection becomes unusable as the first fragment will never be properly verified at the receiver, the MIC is practically guaranteed to be wrong b) we leak up to 8 bytes of plaintext (!) of the packet out into the air This is only mitigated by the fact that many devices are capable of doing encryption in hardware, in which case this can't happen as the tail pointer is irrelevant in that case. Additionally, fragmentation is not used very frequently and would normally have to be configured manually. Fix this by using skb_trim() properly. Fixes: 2de8e0d999b8 ("mac80211: rewrite fragmentation") Reported-by: Jouni Malinen <j@w1.fi> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/mac80211/tx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 1.9.0