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In some case skb->sk != asoc->base.sk: for the trouble SKB, it was in outq->transmitted queue sctp_outq_sack sctp_check_transmitted SKB was moved to outq->sack then throw away the sack queue SKB was deleted from outq->sack (but the datamsg held SKB at sctp_datamsg_to_asoc So, sctp_wfree was not called to destroy SKB) then migrate happened sctp_for_each_tx_datachunk( sctp_clear_owner_w); sctp_assoc_migrate(); sctp_for_each_tx_datachunk( sctp_set_owner_w); SKB was not in the outq, and was not changed to newsk finally __sctp_outq_teardown sctp_chunk_put (for another skb) sctp_datamsg_put __kfree_skb(msg->frag_list) sctp_wfree (for SKB) this case in sctp_wfree SKB->sk was oldsk. It looks only trouble here so handling it in sctp_wfree is enough. Reported-and-tested-by: syzbot+cea71eec5d6de256d54d@syzkaller.appspotmail.com Signed-off-by: Qiujun Huang --- net/sctp/socket.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 1b56fc440606..5f5c28b30e25 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -9080,7 +9080,7 @@ static void sctp_wfree(struct sk_buff *skb) { struct sctp_chunk *chunk = skb_shinfo(skb)->destructor_arg; struct sctp_association *asoc = chunk->asoc; - struct sock *sk = asoc->base.sk; + struct sock *sk = skb->sk; sk_mem_uncharge(sk, skb->truesize); sk->sk_wmem_queued -= skb->truesize + sizeof(struct sctp_chunk); @@ -9109,7 +9109,7 @@ static void sctp_wfree(struct sk_buff *skb) } sock_wfree(skb); - sctp_wake_up_waiters(sk, asoc); + sctp_wake_up_waiters(asoc->base.sk, asoc); sctp_association_put(asoc); } -- 2.17.1