From: Eric Dumazet Date: Sun, 12 Feb 2017 22:03:52 +0000 (-0800) Subject: net/llc: avoid BUG_ON() in skb_orphan() X-Git-Tag: v4.1.12-102.0.20170529_2200~23 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=c64b7f7b8e8d8d91d2576d140edab4e7c64f1133;p=users%2Fjedix%2Flinux-maple.git net/llc: avoid BUG_ON() in skb_orphan() 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. Orabug: 25802599 CVE: CVE-2017-6345 Fixes: 376c7311bdb6 ("net: add a temporary sanity check in skb_orphan()") Signed-off-by: Eric Dumazet Reported-by: Andrey Konovalov Signed-off-by: David S. Miller Signed-off-by: Aniket Alshi (cherry picked from commit 8b74d439e1697110c5e5c600643e823eb1dd0762) Reviewed-by: Jack Vogel --- diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c index f7fc7e7b109be..bd504c3cfe282 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 d0e1e804ebd73..5404d0d195cc5 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); }