4.4-stable review patch. If anyone has any objections, please let me know.
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From: Xin Long lucien.xin@gmail.com
commit df132eff463873e14e019a07f387b4d577d6d1f9 upstream.
If a transport is removed by asconf but there still are some chunks with this transport queuing on out_chunk_list, later an use-after-free issue will be caused when accessing this transport from these chunks in sctp_outq_flush().
This is an old bug, we fix it by clearing the transport of these chunks in out_chunk_list when removing a transport in sctp_assoc_rm_peer().
Reported-by: syzbot+56a40ceee5fb35932f4d@syzkaller.appspotmail.com Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/sctp/associola.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/net/sctp/associola.c +++ b/net/sctp/associola.c @@ -486,8 +486,9 @@ void sctp_assoc_set_primary(struct sctp_ void sctp_assoc_rm_peer(struct sctp_association *asoc, struct sctp_transport *peer) { - struct list_head *pos; - struct sctp_transport *transport; + struct sctp_transport *transport; + struct list_head *pos; + struct sctp_chunk *ch;
pr_debug("%s: association:%p addr:%pISpc\n", __func__, asoc, &peer->ipaddr.sa); @@ -543,7 +544,6 @@ void sctp_assoc_rm_peer(struct sctp_asso */ if (!list_empty(&peer->transmitted)) { struct sctp_transport *active = asoc->peer.active_path; - struct sctp_chunk *ch;
/* Reset the transport of each chunk on this list */ list_for_each_entry(ch, &peer->transmitted, @@ -565,6 +565,10 @@ void sctp_assoc_rm_peer(struct sctp_asso sctp_transport_hold(active); }
+ list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list) + if (ch->transport == peer) + ch->transport = NULL; + asoc->peer.transport_count--;
sctp_transport_free(peer);