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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79D9ECA9EA0 for ; Fri, 25 Oct 2019 14:05:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 52463222BE for ; Fri, 25 Oct 2019 14:05:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572012346; bh=rlocA8g38g9I8z4t3d/Svrv3R3ZY2CKk7/WiK2gEcvw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gTSRsa/v1AcgXsnmlyyRl01OUfRlJ7MNO+/JHJ5x/7OdyJyILyOShVdfz2DNQKWzk c+QkTwNZPymz2ujoL48ppDLRce4b4zmvy9oV3vGCOkxhCK1k2hHnHtl5E/yDDb4Uwj 9UEIwi1MCw1NJb1GcZQIPet7d3T0mCVkwH7RKCOs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2505200AbfJYNz5 (ORCPT ); Fri, 25 Oct 2019 09:55:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:50058 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2505182AbfJYNz4 (ORCPT ); Fri, 25 Oct 2019 09:55:56 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C03AB222C9; Fri, 25 Oct 2019 13:55:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572011754; bh=rlocA8g38g9I8z4t3d/Svrv3R3ZY2CKk7/WiK2gEcvw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PCqDzIM9KKygW74BtKRotsK9mtY07fORKLLuSlE8r5cvktIycnd7OKvjBCT38Bh6A AyE0/UeTZh4V3KpxHRJKCxkO/uui5aSeJCt7DG+PPTKdSE5/OS1duPjnGT3okSbm38 MWqaTWHKz3l/9BEFSSAM48OdeKtI/AahMo95DuFM= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Xin Long , Ying Xu , Marcelo Ricardo Leitner , Neil Horman , Jakub Kicinski , Sasha Levin , linux-sctp@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.3 31/33] sctp: add chunks to sk_backlog when the newsk sk_socket is not set Date: Fri, 25 Oct 2019 09:55:03 -0400 Message-Id: <20191025135505.24762-31-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191025135505.24762-1-sashal@kernel.org> References: <20191025135505.24762-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Xin Long [ Upstream commit 819be8108fded0b9e710bbbf81193e52f7bab2f7 ] This patch is to fix a NULL-ptr deref in selinux_socket_connect_helper: [...] kasan: GPF could be caused by NULL-ptr deref or user memory access [...] RIP: 0010:selinux_socket_connect_helper+0x94/0x460 [...] Call Trace: [...] selinux_sctp_bind_connect+0x16a/0x1d0 [...] security_sctp_bind_connect+0x58/0x90 [...] sctp_process_asconf+0xa52/0xfd0 [sctp] [...] sctp_sf_do_asconf+0x785/0x980 [sctp] [...] sctp_do_sm+0x175/0x5a0 [sctp] [...] sctp_assoc_bh_rcv+0x285/0x5b0 [sctp] [...] sctp_backlog_rcv+0x482/0x910 [sctp] [...] __release_sock+0x11e/0x310 [...] release_sock+0x4f/0x180 [...] sctp_accept+0x3f9/0x5a0 [sctp] [...] inet_accept+0xe7/0x720 It was caused by that the 'newsk' sk_socket was not set before going to security sctp hook when processing asconf chunk with SCTP_PARAM_ADD_IP or SCTP_PARAM_SET_PRIMARY: inet_accept()-> sctp_accept(): lock_sock(): lock listening 'sk' do_softirq(): sctp_rcv(): <-- [1] asconf chunk arrives and enqueued in 'sk' backlog sctp_sock_migrate(): set asoc's sk to 'newsk' release_sock(): sctp_backlog_rcv(): lock 'newsk' sctp_process_asconf() <-- [2] unlock 'newsk' sock_graft(): set sk_socket <-- [3] As it shows, at [1] the asconf chunk would be put into the listening 'sk' backlog, as accept() was holding its sock lock. Then at [2] asconf would get processed with 'newsk' as asoc's sk had been set to 'newsk'. However, 'newsk' sk_socket is not set until [3], while selinux_sctp_bind_connect() would deref it, then kernel crashed. Here to fix it by adding the chunk to sk_backlog until newsk sk_socket is set when .accept() is done. Note that sk->sk_socket can be NULL when the sock is closed, so SOCK_DEAD flag is also needed to check in sctp_newsk_ready(). Thanks to Ondrej for reviewing the code. Fixes: d452930fd3b9 ("selinux: Add SCTP support") Reported-by: Ying Xu Suggested-by: Marcelo Ricardo Leitner Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/sctp/sctp.h | 5 +++++ net/sctp/input.c | 12 +++++++++--- 2 files changed, 14 insertions(+), 3 deletions(-) diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index 5d60f13d2347b..3ab5c6bbb90bd 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -610,4 +610,9 @@ static inline __u32 sctp_min_frag_point(struct sctp_sock *sp, __u16 datasize) return sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT, datasize); } +static inline bool sctp_newsk_ready(const struct sock *sk) +{ + return sock_flag(sk, SOCK_DEAD) || sk->sk_socket; +} + #endif /* __net_sctp_h__ */ diff --git a/net/sctp/input.c b/net/sctp/input.c index 1008cdc44dd61..156e24ad54ea4 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -243,7 +243,7 @@ int sctp_rcv(struct sk_buff *skb) bh_lock_sock(sk); } - if (sock_owned_by_user(sk)) { + if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) { if (sctp_add_backlog(sk, skb)) { bh_unlock_sock(sk); sctp_chunk_free(chunk); @@ -321,7 +321,7 @@ int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) local_bh_disable(); bh_lock_sock(sk); - if (sock_owned_by_user(sk)) { + if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) { if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) sctp_chunk_free(chunk); else @@ -336,7 +336,13 @@ int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) if (backloged) return 0; } else { - sctp_inq_push(inqueue, chunk); + if (!sctp_newsk_ready(sk)) { + if (!sk_add_backlog(sk, skb, sk->sk_rcvbuf)) + return 0; + sctp_chunk_free(chunk); + } else { + sctp_inq_push(inqueue, chunk); + } } done: -- 2.20.1