From patchwork Wed Dec 8 16:54:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lee Jones X-Patchwork-Id: 12664803 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 BD5FAC433EF for ; Wed, 8 Dec 2021 16:54:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237400AbhLHQ6Q (ORCPT ); Wed, 8 Dec 2021 11:58:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237395AbhLHQ6P (ORCPT ); Wed, 8 Dec 2021 11:58:15 -0500 Received: from mail-wr1-x436.google.com (mail-wr1-x436.google.com [IPv6:2a00:1450:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD047C0617A2 for ; Wed, 8 Dec 2021 08:54:43 -0800 (PST) Received: by mail-wr1-x436.google.com with SMTP id v11so5121196wrw.10 for ; Wed, 08 Dec 2021 08:54:43 -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=YN7SopJ792rYSyvS/k6+6PuXkEaW1GUeMvGKCe7x+ik=; b=J+TbOkyt82nIoJaFvHEWgDDTEY6jM1fG04zXfRHK4uHp2LoCSuRsMIvzHPOloJPfsz VaZ1RcPw20Qi/PxMrsxj6bgcTp87z/4dTXl2iA4FcKzjjbgaxslIvg9sdW3R6lTmb4Qy JVx6pAoQfeFiVVqQQc2Paml9c7cm6lLVlywQCauLw8o6e/3gchFs23/TPwxT82ak6mWH /3Hvg6pk8zCXVq+PaJHgcCWiDkz19z9r35eC4ltmWmrBjGCBRQlKs8S96fu7JIEWVitP ypmTeAf6FN8NZyySe4lTY1919vCTLZ39MyJwHM8iKCFaNzMUX06r7RXtEnuHhog3ukVi c2uA== 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=YN7SopJ792rYSyvS/k6+6PuXkEaW1GUeMvGKCe7x+ik=; b=jf51zN66rj9wcUIwRzodqP2+TBacKrjHJyg54ZRfxzyQpaGFSWRWAXadDCqIAUULeX s1zH0RC7UuFEfkOMDydTF2Z82sW+Fz1zYhl7nZvF3yhdRQsZCmJUByBS4txvCrxDSwWx mZqlepvkZ3f2sGv4DJdEhjhvYJjweJCTo9L9H+6DRDCQphLfO0OrS7UftXtJ7L+M17UA DXtiu2g1IU3cPy/ZSlhbrMmq/EbiDOnRJIU+4VAlUmjtA+pW2UIAev9n9teYHw/PlqGi VHJc9DyT3qa4yx3OJPrnj+SCI+UTWIAS3WPvnr8/o0K2kvEoDNw2c0+qPv1mIeK+DoPE B37g== X-Gm-Message-State: AOAM530KllYa/lEqqftmGSvZBX2eHPzS9gUGIdbtnAVryeetl7yf3Cto ymcSCCRc9g6ucBrbvAkaoUwDag== X-Google-Smtp-Source: ABdhPJyCsxaHwjoJGpb1kpKdErG9QngK0st0jPwjBrFDcGdCXFGG2d4SLrzhQROA3gmmJTUxyr0unw== X-Received: by 2002:a5d:64a2:: with SMTP id m2mr61750734wrp.248.1638982482311; Wed, 08 Dec 2021 08:54:42 -0800 (PST) Received: from joneslee.c.googlers.com.com (205.215.190.35.bc.googleusercontent.com. [35.190.215.205]) by smtp.gmail.com with ESMTPSA id y15sm4375735wry.72.2021.12.08.08.54.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Dec 2021 08:54:41 -0800 (PST) From: Lee Jones To: lee.jones@linaro.org Cc: 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 1/1] sctp: Protect cached endpoints to prevent possible UAF Date: Wed, 8 Dec 2021 16:54:34 +0000 Message-Id: <20211208165434.2962062-1-lee.jones@linaro.org> X-Mailer: git-send-email 2.34.1.400.ga245620fadb-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 then freed prior to its subsequent use in sctp_diag_dump() which uses sctp_for_each_transport() to walk the (now out of date) hash table calling into sctp_sock_dump() where the dereference occurs. To prevent this from happening we need to take a reference on the to-be-used/dereferenced 'struct sctp_endpoint' 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. 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 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/associola.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/sctp/associola.c b/net/sctp/associola.c index be29da09cc7ab..df171a297d095 100644 --- a/net/sctp/associola.c +++ b/net/sctp/associola.c @@ -499,8 +499,9 @@ void sctp_assoc_rm_peer(struct sctp_association *asoc, /* Remove this peer from the list. */ list_del_rcu(&peer->transports); - /* Remove this peer from the transport hashtable */ + /* Remove this peer from the transport hashtable and remove its reference */ sctp_unhash_transport(peer); + sctp_endpoint_put(asoc->ep); /* Get the first transport of asoc. */ pos = asoc->peer.transport_addr_list.next; @@ -710,11 +711,12 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc, /* Set the peer's active state. */ peer->state = peer_state; - /* Add this peer into the transport hashtable */ + /* Add this peer into the transport hashtable and take a reference */ if (sctp_hash_transport(peer)) { sctp_transport_free(peer); return NULL; } + sctp_endpoint_hold(asoc->ep); sctp_transport_pl_reset(peer);