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 C84A6C001E0 for ; Mon, 23 Oct 2023 11:16:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233715AbjJWLQe (ORCPT ); Mon, 23 Oct 2023 07:16:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233746AbjJWLQ3 (ORCPT ); Mon, 23 Oct 2023 07:16:29 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BDA9C1 for ; Mon, 23 Oct 2023 04:16:27 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5841C433C8; Mon, 23 Oct 2023 11:16:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1698059787; bh=kEKYuMC+SLXJuuWhxm0RmUNhYcCMG18/qIgjLY3EfZU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eRtbgzsBOX6UJYJ4mIk3nKgvna+dLN5p4jKiWVs0QfpMo/EYyKVCgMtDaaUtvONtl tvpRx07r4QOK4WPEg5KfuaA3V5vHJwiyL4tsLEUTdz0TiEapBIZ03/kwwxzOKSYYhs +OctHHKuQ2f9xdVbcUMr2NElxD/W0D4KLLycqYZg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Eric Dumazet , Steffen Klassert , Herbert Xu Subject: [PATCH 4.19 52/98] xfrm: fix a data-race in xfrm_gen_index() Date: Mon, 23 Oct 2023 12:56:41 +0200 Message-ID: <20231023104815.448047498@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231023104813.580375891@linuxfoundation.org> References: <20231023104813.580375891@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 3e4bc23926b83c3c67e5f61ae8571602754131a6 upstream. xfrm_gen_index() mutual exclusion uses net->xfrm.xfrm_policy_lock. This means we must use a per-netns idx_generator variable, instead of a static one. Alternative would be to use an atomic variable. syzbot reported: BUG: KCSAN: data-race in xfrm_sk_policy_insert / xfrm_sk_policy_insert write to 0xffffffff87005938 of 4 bytes by task 29466 on cpu 0: xfrm_gen_index net/xfrm/xfrm_policy.c:1385 [inline] xfrm_sk_policy_insert+0x262/0x640 net/xfrm/xfrm_policy.c:2347 xfrm_user_policy+0x413/0x540 net/xfrm/xfrm_state.c:2639 do_ipv6_setsockopt+0x1317/0x2ce0 net/ipv6/ipv6_sockglue.c:943 ipv6_setsockopt+0x57/0x130 net/ipv6/ipv6_sockglue.c:1012 rawv6_setsockopt+0x21e/0x410 net/ipv6/raw.c:1054 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697 __sys_setsockopt+0x1c9/0x230 net/socket.c:2263 __do_sys_setsockopt net/socket.c:2274 [inline] __se_sys_setsockopt net/socket.c:2271 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2271 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd read to 0xffffffff87005938 of 4 bytes by task 29460 on cpu 1: xfrm_sk_policy_insert+0x13e/0x640 xfrm_user_policy+0x413/0x540 net/xfrm/xfrm_state.c:2639 do_ipv6_setsockopt+0x1317/0x2ce0 net/ipv6/ipv6_sockglue.c:943 ipv6_setsockopt+0x57/0x130 net/ipv6/ipv6_sockglue.c:1012 rawv6_setsockopt+0x21e/0x410 net/ipv6/raw.c:1054 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697 __sys_setsockopt+0x1c9/0x230 net/socket.c:2263 __do_sys_setsockopt net/socket.c:2274 [inline] __se_sys_setsockopt net/socket.c:2271 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2271 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0x00006ad8 -> 0x00006b18 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 29460 Comm: syz-executor.1 Not tainted 6.5.0-rc5-syzkaller-00243-g9106536c1aa3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023 Fixes: 1121994c803f ("netns xfrm: policy insertion in netns") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Steffen Klassert Cc: Herbert Xu Acked-by: Herbert Xu Signed-off-by: Steffen Klassert Signed-off-by: Greg Kroah-Hartman --- include/net/netns/xfrm.h | 1 + net/xfrm/xfrm_policy.c | 6 ++---- 2 files changed, 3 insertions(+), 4 deletions(-) --- a/include/net/netns/xfrm.h +++ b/include/net/netns/xfrm.h @@ -48,6 +48,7 @@ struct netns_xfrm { struct list_head policy_all; struct hlist_head *policy_byidx; unsigned int policy_idx_hmask; + unsigned int idx_generator; struct hlist_head policy_inexact[XFRM_POLICY_MAX]; struct xfrm_policy_hash policy_bydst[XFRM_POLICY_MAX]; unsigned int policy_count[XFRM_POLICY_MAX * 2]; --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -654,8 +654,6 @@ EXPORT_SYMBOL(xfrm_policy_hash_rebuild); * of an absolute inpredictability of ordering of rules. This will not pass. */ static u32 xfrm_gen_index(struct net *net, int dir, u32 index) { - static u32 idx_generator; - for (;;) { struct hlist_head *list; struct xfrm_policy *p; @@ -663,8 +661,8 @@ static u32 xfrm_gen_index(struct net *ne int found; if (!index) { - idx = (idx_generator | dir); - idx_generator += 8; + idx = (net->xfrm.idx_generator | dir); + net->xfrm.idx_generator += 8; } else { idx = index; index = 0;