From mboxrd@z Thu Jan 1 00:00:00 1970 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 1A456C19F2D for ; Tue, 9 Aug 2022 09:45:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235758AbiHIJpw (ORCPT ); Tue, 9 Aug 2022 05:45:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232584AbiHIJpw (ORCPT ); Tue, 9 Aug 2022 05:45:52 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1F251F636; Tue, 9 Aug 2022 02:45:50 -0700 (PDT) Received: from canpemm500010.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4M27S100S2zmVY4; Tue, 9 Aug 2022 17:43:44 +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, 9 Aug 2022 17:45:47 +0800 From: Liu Jian To: , , , , , , , , , CC: Subject: [PATCH bpf-next v2] skmsg: Fix wrong last sg check in sk_msg_recvmsg() Date: Tue, 9 Aug 2022 17:49:15 +0800 Message-ID: <20220809094915.150391-1-liujian56@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500010.china.huawei.com (7.192.105.118) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Fix one kernel NULL pointer dereference as below: [ 224.462334] Call Trace: [ 224.462394] __tcp_bpf_recvmsg+0xd3/0x380 [ 224.462441] ? sock_has_perm+0x78/0xa0 [ 224.462463] tcp_bpf_recvmsg+0x12e/0x220 [ 224.462494] inet_recvmsg+0x5b/0xd0 [ 224.462534] __sys_recvfrom+0xc8/0x130 [ 224.462574] ? syscall_trace_enter+0x1df/0x2e0 [ 224.462606] ? __do_page_fault+0x2de/0x500 [ 224.462635] __x64_sys_recvfrom+0x24/0x30 [ 224.462660] do_syscall_64+0x5d/0x1d0 [ 224.462709] entry_SYSCALL_64_after_hwframe+0x65/0xca In commit 9974d37ea75f ("skmsg: Fix invalid last sg check in sk_msg_recvmsg()"), we change last sg check to sg_is_last(), but in sockmap redirection case (without stream_parser/stream_verdict/ skb_verdict), we did not mark the end of the scatterlist. Check the sk_msg_alloc, sk_msg_page_add, and bpf_msg_push_data functions, they all do not mark the end of sg. They are expected to use sg.end for end judgment. So the judgment of '(i != msg_rx->sg.end)' is added back here. Fixes: 9974d37ea75f ("skmsg: Fix invalid last sg check in sk_msg_recvmsg()") Signed-off-by: Liu Jian --- v1->v2: change fix commit info in fixes tag and commit message. 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 81627892bdd4..385ae23580a5 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 (!sg_is_last(sge)); + } while ((i != msg_rx->sg.end) && !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 && sg_is_last(sge)) { + if (!sge->length && (i == msg_rx->sg.end || sg_is_last(sge))) { msg_rx = sk_psock_dequeue_msg(psock); kfree_sk_msg(msg_rx); } -- 2.17.1