From: Xin Long <lucien.xin@gmail.com> mainline inclusion from mainline-v5.15 commit a64b341b8695e1c744dd972b39868371b4f68f83 category: bugfix bugzilla: NA CVE: CVE-2021-3772 ------------------------------------------------- 1. In closed state: in sctp_sf_do_5_1D_ce(): When asoc is NULL, making packet for abort will use chunk's vtag in sctp_ootb_pkt_new(). But when asoc exists, vtag from the chunk should be verified before using peer.i.init_tag to make packet for abort in sctp_ootb_pkt_new(), and just discard it if vtag is not correct. 2. In the other states: in sctp_sf_do_5_2_4_dupcook(): asoc always exists, but duplicate cookie_echo's vtag will be handled by sctp_tietags_compare() and then take actions, so before that we only verify the vtag for the abort sent for invalid chunk length. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xin Long <lucien.xin@gmail.com> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Huang Guobin <huangguobin4@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Reviewed-by: Yue Haibing <yuehaibing@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- net/sctp/sm_statefuns.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index b2482a39b7a7e..aed5b3e09b68c 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -718,6 +718,9 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net, struct sock *sk; int error = 0; + if (asoc && !sctp_vtag_verify(chunk, asoc)) + return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); + /* If the packet is an OOTB packet which is temporarily on the * control endpoint, respond with an ABORT. */ @@ -732,7 +735,8 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net, * in sctp_unpack_cookie(). */ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr))) - return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); + return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, + commands); /* If the endpoint is not listening or if the number of associations * on the TCP-style socket exceed the max backlog, respond with an @@ -2159,9 +2163,11 @@ enum sctp_disposition sctp_sf_do_5_2_4_dupcook( * enough for the chunk header. Cookie length verification is * done later. */ - if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr))) - return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, - commands); + if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr))) { + if (!sctp_vtag_verify(chunk, asoc)) + asoc = NULL; + return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); + } /* "Decode" the chunk. We have no optional parameters so we * are in good shape. -- 2.25.1