From: Xin Long <lucien.xin@gmail.com> mainline inclusion from mainline-v5.15 commit 9d02831e517aa36ee6bdb453a0eb47bd49923fe3 category: bugfix bugzilla: NA CVE: CVE-2021-3772 ------------------------------------------------- sctp_sf_ootb() is called when processing DATA chunk in closed state, and many other places are also using it. The vtag in the chunk's sctphdr should be verified, otherwise, as later in chunk length check, it may send abort with the existent asoc's vtag, which can be exploited by one to cook a malicious chunk to terminate a SCTP asoc. When fails to verify the vtag from the chunk, this patch sets asoc to NULL, so that the abort will be made with the vtag from the received chunk later. 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: Yue Haibing <yuehaibing@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- net/sctp/sm_statefuns.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index aed1db9ff01dc..373be2a1be7d0 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -3604,6 +3604,9 @@ enum sctp_disposition sctp_sf_ootb(struct net *net, SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); + if (asoc && !sctp_vtag_verify(chunk, asoc)) + asoc = NULL; + ch = (struct sctp_chunkhdr *)chunk->chunk_hdr; do { /* Report violation if the chunk is less then minimal */ -- 2.25.1