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authorEric Dumazet <edumazet@google.com>2017-02-12 14:03:52 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-26 11:10:50 +0100
commit42b52783a59cc706c71cdc7096edce4a6f086fd3 (patch)
tree7a5debd3bf6fcaf24a0c253449f5c3b039a2bf61
parent859900c24bff90768e1789bd93e1b51fa726a659 (diff)
net/llc: avoid BUG_ON() in skb_orphan()
[ Upstream commit 8b74d439e1697110c5e5c600643e823eb1dd0762 ] It seems nobody used LLC since linux-3.12. Fortunately fuzzers like syzkaller still know how to run this code, otherwise it would be no fun. Setting skb->sk without skb->destructor leads to all kinds of bugs, we now prefer to be very strict about it. Ideally here we would use skb_set_owner() but this helper does not exist yet, only CAN seems to have a private helper for that. Fixes: 376c7311bdb6 ("net: add a temporary sanity check in skb_orphan()") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/llc/llc_conn.c3
-rw-r--r--net/llc/llc_sap.c3
2 files changed, 6 insertions, 0 deletions
diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
index 3e821daf9dd4..8bc5a1bd2d45 100644
--- a/net/llc/llc_conn.c
+++ b/net/llc/llc_conn.c
@@ -821,7 +821,10 @@ void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
* another trick required to cope with how the PROCOM state
* machine works. -acme
*/
+ skb_orphan(skb);
+ sock_hold(sk);
skb->sk = sk;
+ skb->destructor = sock_efree;
}
if (!sock_owned_by_user(sk))
llc_conn_rcv(sk, skb);
diff --git a/net/llc/llc_sap.c b/net/llc/llc_sap.c
index d0e1e804ebd7..5404d0d195cc 100644
--- a/net/llc/llc_sap.c
+++ b/net/llc/llc_sap.c
@@ -290,7 +290,10 @@ static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
ev->type = LLC_SAP_EV_TYPE_PDU;
ev->reason = 0;
+ skb_orphan(skb);
+ sock_hold(sk);
skb->sk = sk;
+ skb->destructor = sock_efree;
llc_sap_state_process(sap, skb);
}