From patchwork Tue Jun 28 12:36:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liu Jian X-Patchwork-Id: 12898201 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1AE0C43334 for ; Tue, 28 Jun 2022 12:31:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345829AbiF1MbE (ORCPT ); Tue, 28 Jun 2022 08:31:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345827AbiF1MbD (ORCPT ); Tue, 28 Jun 2022 08:31:03 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73AB02E9C3; Tue, 28 Jun 2022 05:31:02 -0700 (PDT) Received: from canpemm500010.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4LXP4M00w2zTgG7; Tue, 28 Jun 2022 20:27:30 +0800 (CST) Received: from huawei.com (10.175.101.6) by canpemm500010.china.huawei.com (7.192.105.118) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 28 Jun 2022 20:30:59 +0800 From: Liu Jian To: , , , , , , , , , , , , , , CC: Subject: [PATCH bpf] skmsg: Fix invalid last sg check in sk_msg_recvmsg() Date: Tue, 28 Jun 2022 20:36:16 +0800 Message-ID: <20220628123616.186950-1-liujian56@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500010.china.huawei.com (7.192.105.118) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net In sk_psock_skb_ingress_enqueue function, if the linear area + nr_frags + frag_list of the SKB has NR_MSG_FRAG_IDS blocks in total, skb_to_sgvec will return NR_MSG_FRAG_IDS, then msg->sg.end will be set to NR_MSG_FRAG_IDS, and in addition, (NR_MSG_FRAG_IDS - 1) is set to the last SG of msg. Recv the msg in sk_msg_recvmsg, when i is (NR_MSG_FRAG_IDS - 1), the sk_msg_iter_var_next(i) will change i to 0 (not NR_MSG_FRAG_IDS), the judgment condition "msg_rx->sg.start==msg_rx->sg.end" and "i != msg_rx->sg.end" can not work. As a result, the processed msg cannot be deleted from ingress_msg list. But the length of all the sge of the msg has changed to 0. Then the next recvmsg syscall will process the msg repeatedly, because the length of sge is 0, the -EFAULT error is always returned. Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Liu Jian Acked-by: John Fastabend --- net/core/skmsg.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index b0fcd0200e84..a8dbea559c7f 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -462,7 +462,7 @@ int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg, if (copied == len) break; - } while (i != msg_rx->sg.end); + } while (!sg_is_last(sge)); if (unlikely(peek)) { msg_rx = sk_psock_next_msg(psock, msg_rx); @@ -472,7 +472,7 @@ int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg, } msg_rx->sg.start = i; - if (!sge->length && msg_rx->sg.start == msg_rx->sg.end) { + if (!sge->length && sg_is_last(sge)) { msg_rx = sk_psock_dequeue_msg(psock); kfree_sk_msg(msg_rx); }