From patchwork Tue Dec 14 19:23:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lee Jones X-Patchwork-Id: 12676611 X-Patchwork-Delegate: kuba@kernel.org 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 57FD1C433F5 for ; Tue, 14 Dec 2021 19:23:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237366AbhLNTXJ (ORCPT ); Tue, 14 Dec 2021 14:23:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229671AbhLNTXI (ORCPT ); Tue, 14 Dec 2021 14:23:08 -0500 Received: from mail-wr1-x429.google.com (mail-wr1-x429.google.com [IPv6:2a00:1450:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E8BAC06173E for ; Tue, 14 Dec 2021 11:23:08 -0800 (PST) Received: by mail-wr1-x429.google.com with SMTP id v11so34144345wrw.10 for ; Tue, 14 Dec 2021 11:23:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9MfX+ladgz8v1uPlUvt81YDUVI2BVYjumD0vKwEPZL8=; b=WqDW2eYz3b7YYPBATttXaZ6buiyp4VM0CVsPBNwqwvYXLJqSfLdSDpj5RehBf1rzm8 0NGFCRKTByBHutzxvd6c3nFRfg7S5gUxzyjAsZRCB6ZNpHiZ2kV4SDb8uD7YJDElQvlZ OKIIpRv009ozrHeUDnGuQDG22K2U2mBGC0ta7+gNfXDSXxmilG4PK8PLbtJqfFIzJDBA z8MvgBO9eoTIaFj2zVPC3py7D9VrBVFftahzSaKfwtYSDwwnGClk+GUSkt5Geu8DLPDe AYpoiIGXYQQWCabokDuhcVDYZs+WEqYPRuJCe9jGgGOnOOBFi7boE3CqCm1HAkh3//a8 O05g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9MfX+ladgz8v1uPlUvt81YDUVI2BVYjumD0vKwEPZL8=; b=oVEpUkhp/UtAvUTVM52jBLqocR4CB2awtFwJqCWXXZX8dFW+2moffSAdJXne1mfGRO vULe2gZ54Y3BFuhLRopxcHN4AuB0/iLWqVWcouiZNGs20/yEUHrZN9ArHA0jhm41KVZ8 PRmWdjKeEjn1C4wdv8EC0QmGf6gVb6yizIWpeBBi3QJnyXhpLiiTdc+93Fp5a+coSx/7 T7hYYsRQ2jYH4jBgw7DC6ouOrh9iBJ2TTQN9asJqf+9Q/sNCnM0D0WKPOaW+VzSgEMIz lVzU7RrznoZQJgfpKoyCN4Zmih4fjpXdqSjrO2T3/XIMWGVsVgC2g8+jJa8mpqgXabCK Y1Fw== X-Gm-Message-State: AOAM531nbU7QbOsHIySvNzcsdh6H0yaivBAnpm5XOEcxqRRQCNf3IhYj 737zm4stp5eyhWnWPIHyA+jzUg== X-Google-Smtp-Source: ABdhPJwoBMoW5TWXaHsl8SQQzk0cq/QVYi0kpQ4LMnACrafWI+8XOMMdce8J0U4u6zLy20HzGg6EZA== X-Received: by 2002:a5d:6211:: with SMTP id y17mr1055106wru.97.1639509786687; Tue, 14 Dec 2021 11:23:06 -0800 (PST) Received: from localhost.localdomain ([2.31.167.18]) by smtp.gmail.com with ESMTPSA id d7sm672169wrw.87.2021.12.14.11.23.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Dec 2021 11:23:06 -0800 (PST) From: Lee Jones To: lee.jones@linaro.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Vlad Yasevich , Neil Horman , Marcelo Ricardo Leitner , "David S. Miller" , Jakub Kicinski , lksctp developers , "H.P. Yarroll" , Karl Knutson , Jon Grimm , Xingang Guo , Hui Huang , Sridhar Samudrala , Daisy Chang , Ryan Layer , Kevin Gao , netdev@vger.kernel.org Subject: [PATCH 2/2] sctp: hold cached endpoints to prevent possible UAF Date: Tue, 14 Dec 2021 19:23:01 +0000 Message-Id: <20211214192301.1496754-1-lee.jones@linaro.org> X-Mailer: git-send-email 2.34.1.173.g76aa8bc2d0-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The cause of the resultant dump_stack() reported below is a dereference of a freed pointer to 'struct sctp_endpoint' in sctp_sock_dump(). This race condition occurs when a transport is cached into its associated hash table followed by an endpoint/sock migration to a new association in sctp_assoc_migrate() prior to their subsequent use in sctp_diag_dump() which uses sctp_for_each_transport() to walk the hash table calling into sctp_sock_dump() where the dereference occurs. BUG: KASAN: use-after-free in sctp_sock_dump+0xa8/0x438 [sctp_diag] Call trace: dump_backtrace+0x0/0x2dc show_stack+0x20/0x2c dump_stack+0x120/0x144 print_address_description+0x80/0x2f4 __kasan_report+0x174/0x194 kasan_report+0x10/0x18 __asan_load8+0x84/0x8c sctp_sock_dump+0xa8/0x438 [sctp_diag] sctp_for_each_transport+0x1e0/0x26c [sctp] sctp_diag_dump+0x180/0x1f0 [sctp_diag] inet_diag_dump+0x12c/0x168 netlink_dump+0x24c/0x5b8 __netlink_dump_start+0x274/0x2a8 inet_diag_handler_cmd+0x224/0x274 sock_diag_rcv_msg+0x21c/0x230 netlink_rcv_skb+0xe0/0x1bc sock_diag_rcv+0x34/0x48 netlink_unicast+0x3b4/0x430 netlink_sendmsg+0x4f0/0x574 sock_write_iter+0x18c/0x1f0 do_iter_readv_writev+0x230/0x2a8 do_iter_write+0xc8/0x2b4 vfs_writev+0xf8/0x184 do_writev+0xb0/0x1a8 __arm64_sys_writev+0x4c/0x5c el0_svc_common+0x118/0x250 el0_svc_handler+0x3c/0x9c el0_svc+0x8/0xc To prevent this from happening we need to take a references to the to-be-used/dereferenced 'struct sock' and 'struct sctp_endpoint's until such a time when we know it can be safely released. When KASAN is not enabled, a similar, but slightly different NULL pointer derefernce crash occurs later along the thread of execution in inet_sctp_diag_fill() this time. Cc: Vlad Yasevich Cc: Neil Horman Cc: Marcelo Ricardo Leitner Cc: "David S. Miller" Cc: Jakub Kicinski Cc: lksctp developers Cc: "H.P. Yarroll" Cc: Karl Knutson Cc: Jon Grimm Cc: Xingang Guo Cc: Hui Huang Cc: Sridhar Samudrala Cc: Daisy Chang Cc: Ryan Layer Cc: Kevin Gao Cc: linux-sctp@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Lee Jones --- net/sctp/diag.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sctp/diag.c b/net/sctp/diag.c index 760b367644c12..2029b240b6f24 100644 --- a/net/sctp/diag.c +++ b/net/sctp/diag.c @@ -301,6 +301,8 @@ static int sctp_sock_dump(struct sctp_transport *tsp, void *p) struct sctp_association *assoc; int err = 0; + sctp_endpoint_hold(ep); + sock_hold(sk); lock_sock(sk); list_for_each_entry(assoc, &ep->asocs, asocs) { if (cb->args[4] < cb->args[1]) @@ -341,6 +343,8 @@ static int sctp_sock_dump(struct sctp_transport *tsp, void *p) cb->args[4] = 0; release: release_sock(sk); + sock_put(sk); + sctp_endpoint_put(ep); return err; }