| From | Ben Hutchings <> | Date | Fri, 10 Mar 2017 11:46:23 +0000 | Subject | [PATCH 3.16 295/370] net/llc: avoid BUG_ON() in skb_orphan() |
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3.16.42-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
commit 8b74d439e1697110c5e5c600643e823eb1dd0762 upstream.
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: Ben Hutchings <ben@decadent.org.uk> --- net/llc/llc_conn.c | 3 +++ net/llc/llc_sap.c | 3 +++ 2 files changed, 6 insertions(+)
--- a/net/llc/llc_conn.c +++ b/net/llc/llc_conn.c @@ -821,7 +821,10 @@ void llc_conn_handler(struct llc_sap *sa * 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); --- a/net/llc/llc_sap.c +++ b/net/llc/llc_sap.c @@ -290,7 +290,10 @@ static void llc_sap_rcv(struct llc_sap * 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); }
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