Commit 5c3e82fe authored by Qiujun Huang's avatar Qiujun Huang Committed by David S. Miller
Browse files

sctp: fix refcount bug in sctp_wfree 



We should iterate over the datamsgs to move
all chunks(skbs) to newsk.

The following case cause the bug:
for the trouble SKB, it was in outq->transmitted list

sctp_outq_sack
        sctp_check_transmitted
                SKB was moved to outq->sacked list
        then throw away the sack queue
                SKB was deleted from outq->sacked
(but it was held by datamsg at sctp_datamsg_to_asoc
So, sctp_wfree was not called here)

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)
	SKB->sk was still oldsk (skb->sk != asoc->base.sk).

Reported-and-tested-by: default avatar <syzbot+cea71eec5d6de256d54d@syzkaller.appspotmail.com>
Signed-off-by: default avatarQiujun Huang <hqjagain@gmail.com>
Acked-by: default avatarMarcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent fbe4e0c1

net/sctp/socket.c

+23 −8
Original line number Diff line number Diff line
@@ -147,29 +147,44 @@ static void sctp_clear_owner_w(struct sctp_chunk *chunk) 
	skb_orphan(chunk->skb);

}



#define traverse_and_process()	\

do {				\

	msg = chunk->msg;	\

	if (msg == prev_msg)	\

		continue;	\

	list_for_each_entry(c, &msg->chunks, frag_list) {	\

		if ((clear && asoc->base.sk == c->skb->sk) ||	\

		    (!clear && asoc->base.sk != c->skb->sk))	\

			cb(c);	\

	}			\

	prev_msg = msg;		\

} while (0)



static void sctp_for_each_tx_datachunk(struct sctp_association *asoc,

				       bool clear,

				       void (*cb)(struct sctp_chunk *))



{

	struct sctp_datamsg *msg, *prev_msg = NULL;

	struct sctp_outq *q = &asoc->outqueue;

	struct sctp_chunk *chunk, *c;

	struct sctp_transport *t;

	struct sctp_chunk *chunk;



	list_for_each_entry(t, &asoc->peer.transport_addr_list, transports)

		list_for_each_entry(chunk, &t->transmitted, transmitted_list)

			cb(chunk);

			traverse_and_process();



	list_for_each_entry(chunk, &q->retransmit, transmitted_list)

		cb(chunk);

		traverse_and_process();



	list_for_each_entry(chunk, &q->sacked, transmitted_list)

		cb(chunk);

		traverse_and_process();



	list_for_each_entry(chunk, &q->abandoned, transmitted_list)

		cb(chunk);

		traverse_and_process();



	list_for_each_entry(chunk, &q->out_chunk_list, list)

		cb(chunk);

		traverse_and_process();

}



static void sctp_for_each_rx_skb(struct sctp_association *asoc, struct sock *sk,
@@ -9574,9 +9589,9 @@ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk, 
	 * paths won't try to lock it and then oldsk.

	 */

	lock_sock_nested(newsk, SINGLE_DEPTH_NESTING);

	sctp_for_each_tx_datachunk(assoc, sctp_clear_owner_w);

	sctp_for_each_tx_datachunk(assoc, true, sctp_clear_owner_w);

	sctp_assoc_migrate(assoc, newsk);

	sctp_for_each_tx_datachunk(assoc, sctp_set_owner_w);

	sctp_for_each_tx_datachunk(assoc, false, sctp_set_owner_w);



	/* If the association on the newsk is already closed before accept()

	 * is called, set RCV_SHUTDOWN flag.

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