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| author | Jun Yang <junvyyang@tencent.com> | 2026-07-21 16:14:05 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-08-03 12:15:29 +0300 |
| commit | fedeb4468987bcaff85fe3061de5ae052d414740 (patch) | |
| tree | 584db98dcf327c9ea28947689c0f88baf724a4ec | |
| parent | 3422658308d160b1de9c8d38c6f17b17c6d61627 (diff) | |
| download | linux-fedeb4468987bcaff85fe3061de5ae052d414740.tar.xz | |
sctp: don't free the ASCONF's own transport in DEL-IP processing
commit 9b2854f86f0b56e9027d68e7a3fc909d1a9b566f upstream.
sctp_process_asconf() caches the transport the ASCONF chunk is processed
against in asconf->transport (== chunk->transport, set once in sctp_rcv()).
For an ASCONF located through its Address Parameter by
__sctp_rcv_asconf_lookup(), that cached transport corresponds to the
Address Parameter, which need not be the packet's source address.
sctp_process_asconf_param() rejects a DEL-IP for the packet source address
(ADDIP D8, SCTP_ERROR_DEL_SRC_IP), but nothing protects asconf->transport.
A single ASCONF can therefore carry, in order:
[Address Parameter L] [DEL-IP L] [DEL-IP 0.0.0.0]
where L differs from the source. The DEL-IP for L passes the D8 check and
calls sctp_assoc_rm_peer() on the transport that asconf->transport still
points at, freeing it (RCU-deferred). The following wildcard DEL-IP then
reuses the now-dangling asconf->transport in sctp_assoc_set_primary() and
sctp_assoc_del_nonprimary_peers(): set_primary() dereferences the freed
transport (->ipaddr, ->state) and plants the dangling pointer into
asoc->peer.primary_path / active_path, and del_nonprimary_peers(), keeping
only the pointer that is no longer on the list, removes every real
transport, leaving the association with a transport_count of 0 and
primary_path/active_path pointing at freed memory.
Reject a DEL-IP that targets the transport the ASCONF is being processed
against, mirroring the existing source-address guard, so the wildcard
branch can never reuse a freed transport.
Fixes: 42e30bf3463c ("[SCTP]: Handle the wildcard ADD-IP Address parameter")
Cc: stable@kernel.org
Signed-off-by: Jun Yang <junvyyang@tencent.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/tencent_73762ED1DF08CC9D5F5F61954B01350CFE0A@qq.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/sctp/sm_make_chunk.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c index 611bddad36d4..9ed8f502a9c1 100644 --- a/net/sctp/sm_make_chunk.c +++ b/net/sctp/sm_make_chunk.c @@ -3171,6 +3171,12 @@ static __be16 sctp_process_asconf_param(struct sctp_association *asoc, if (!peer) return SCTP_ERROR_DNS_FAILED; + /* Don't free asconf->transport; a later wildcard DEL-IP + * parameter reuses it. + */ + if (peer == asconf->transport) + return SCTP_ERROR_REQ_REFUSED; + sctp_assoc_rm_peer(asoc, peer); break; case SCTP_PARAM_SET_PRIMARY: |