From: Wang Hai <wanghai38@huawei.com> mainline inclusion from mainline-v6.14-rc5 commit 8d52da23b6c68a0f6bad83959ebb61a2cf623c4e category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBN5ZW CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ------------------------------------------------- Recently a bug was discovered where the server had entered TCP_ESTABLISHED state, but the upper layers were not notified. The same 5-tuple packet may be processed by different CPUSs, so two CPUs may receive different ack packets at the same time when the state is TCP_NEW_SYN_RECV. In that case, req->ts_recent in tcp_check_req may be changed concurrently, which will probably cause the newsk's ts_recent to be incorrectly large. So that tcp_validate_incoming will fail. At this point, newsk will not be able to enter the TCP_ESTABLISHED. cpu1 cpu2 tcp_check_req tcp_check_req req->ts_recent = rcv_tsval = t1 req->ts_recent = rcv_tsval = t2 syn_recv_sock tcp_sk(child)->rx_opt.ts_recent = req->ts_recent = t2 // t1 < t2 tcp_child_process tcp_rcv_state_process tcp_validate_incoming tcp_paws_check if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) // t2 - t1 > paws_win, failed tcp_v4_do_rcv tcp_rcv_state_process // TCP_ESTABLISHED The cpu2's skb or a newly received skb will call tcp_v4_do_rcv to get the newsk into the TCP_ESTABLISHED state, but at this point it is no longer possible to notify the upper layer application. A notification mechanism could be added here, but the fix is more complex, so the current fix is used. In tcp_check_req, req->ts_recent is used to assign a value to tcp_sk(child)->rx_opt.ts_recent, so removing the change in req->ts_recent and changing tcp_sk(child)->rx_opt.ts_recent directly after owning the req fixes this bug. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Wang Hai <wanghai38@huawei.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net> Conflicts: net/ipv4/tcp_minisocks.c [Did not backport d4f2c86b2b7e2.] Signed-off-by: Liu Jian <liujian56@huawei.com> --- net/ipv4/tcp_minisocks.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index e2dbc9ab892a..f121307c0cb5 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -743,9 +743,6 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, /* In sequence, PAWS is OK. */ - if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_nxt)) - req->ts_recent = tmp_opt.rcv_tsval; - if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) { /* Truncate SYN, it is out of window starting at tcp_rsk(req)->rcv_isn + 1. */ @@ -794,6 +791,10 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, if (!child) goto listen_overflow; + if (own_req && tmp_opt.saw_tstamp && + !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_nxt)) + tcp_sk(child)->rx_opt.ts_recent = tmp_opt.rcv_tsval; + sock_rps_save_rxhash(child, skb); tcp_synack_rtt_meas(child, req); *req_stolen = !own_req; -- 2.34.1