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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 26B12C49EA7 for ; Mon, 21 Jun 2021 16:48:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 160F26128A for ; Mon, 21 Jun 2021 16:48:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233335AbhFUQte (ORCPT ); Mon, 21 Jun 2021 12:49:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:38048 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233831AbhFUQpf (ORCPT ); Mon, 21 Jun 2021 12:45:35 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 21B0E61369; Mon, 21 Jun 2021 16:32:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624293157; bh=l+y3EfbZGUT0PhyUh4Dy88/m/60AmB8eIKoRxFtmZ1E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2qn7+w/ReTTz9aue9Mn8xjplqUrpuV0qonZAsokN5UXILwR6IO0vCgayJc4fxYHWQ Olnw9S/hG+KdJvI2k0i5+Dq2Z5e+aegM+ziiLcropiIzLc/6zoFrMkTGSBsuPPi+LA MO1m+bh1enBJt22E7dbLh5s2yRlEVVii2CAAg5yI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hillf Danton , syzbot+220c1a29987a9a490903@syzkaller.appspotmail.com, syzbot+45199c1b73b4013525cf@syzkaller.appspotmail.com, Oleksij Rempel , Marc Kleine-Budde Subject: [PATCH 5.12 119/178] can: j1939: fix Use-after-Free, hold skb ref while in use Date: Mon, 21 Jun 2021 18:15:33 +0200 Message-Id: <20210621154926.825722598@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210621154921.212599475@linuxfoundation.org> References: <20210621154921.212599475@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oleksij Rempel commit 2030043e616cab40f510299f09b636285e0a3678 upstream. This patch fixes a Use-after-Free found by the syzbot. The problem is that a skb is taken from the per-session skb queue, without incrementing the ref count. This leads to a Use-after-Free if the skb is taken concurrently from the session queue due to a CTS. Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol") Link: https://lore.kernel.org/r/20210521115720.7533-1-o.rempel@pengutronix.de Cc: Hillf Danton Cc: linux-stable Reported-by: syzbot+220c1a29987a9a490903@syzkaller.appspotmail.com Reported-by: syzbot+45199c1b73b4013525cf@syzkaller.appspotmail.com Signed-off-by: Oleksij Rempel Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- net/can/j1939/transport.c | 54 ++++++++++++++++++++++++++++++++++------------ 1 file changed, 40 insertions(+), 14 deletions(-) --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -330,6 +330,9 @@ static void j1939_session_skb_drop_old(s if ((do_skcb->offset + do_skb->len) < offset_start) { __skb_unlink(do_skb, &session->skb_queue); + /* drop ref taken in j1939_session_skb_queue() */ + skb_unref(do_skb); + kfree_skb(do_skb); } spin_unlock_irqrestore(&session->skb_queue.lock, flags); @@ -349,12 +352,13 @@ void j1939_session_skb_queue(struct j193 skcb->flags |= J1939_ECU_LOCAL_SRC; + skb_get(skb); skb_queue_tail(&session->skb_queue, skb); } static struct -sk_buff *j1939_session_skb_find_by_offset(struct j1939_session *session, - unsigned int offset_start) +sk_buff *j1939_session_skb_get_by_offset(struct j1939_session *session, + unsigned int offset_start) { struct j1939_priv *priv = session->priv; struct j1939_sk_buff_cb *do_skcb; @@ -371,6 +375,10 @@ sk_buff *j1939_session_skb_find_by_offse skb = do_skb; } } + + if (skb) + skb_get(skb); + spin_unlock_irqrestore(&session->skb_queue.lock, flags); if (!skb) @@ -381,12 +389,12 @@ sk_buff *j1939_session_skb_find_by_offse return skb; } -static struct sk_buff *j1939_session_skb_find(struct j1939_session *session) +static struct sk_buff *j1939_session_skb_get(struct j1939_session *session) { unsigned int offset_start; offset_start = session->pkt.dpo * 7; - return j1939_session_skb_find_by_offset(session, offset_start); + return j1939_session_skb_get_by_offset(session, offset_start); } /* see if we are receiver @@ -776,7 +784,7 @@ static int j1939_session_tx_dat(struct j int ret = 0; u8 dat[8]; - se_skb = j1939_session_skb_find_by_offset(session, session->pkt.tx * 7); + se_skb = j1939_session_skb_get_by_offset(session, session->pkt.tx * 7); if (!se_skb) return -ENOBUFS; @@ -801,7 +809,8 @@ static int j1939_session_tx_dat(struct j netdev_err_once(priv->ndev, "%s: 0x%p: requested data outside of queued buffer: offset %i, len %i, pkt.tx: %i\n", __func__, session, skcb->offset, se_skb->len , session->pkt.tx); - return -EOVERFLOW; + ret = -EOVERFLOW; + goto out_free; } if (!len) { @@ -835,6 +844,12 @@ static int j1939_session_tx_dat(struct j if (pkt_done) j1939_tp_set_rxtimeout(session, 250); + out_free: + if (ret) + kfree_skb(se_skb); + else + consume_skb(se_skb); + return ret; } @@ -1007,7 +1022,7 @@ static int j1939_xtp_txnext_receiver(str static int j1939_simple_txnext(struct j1939_session *session) { struct j1939_priv *priv = session->priv; - struct sk_buff *se_skb = j1939_session_skb_find(session); + struct sk_buff *se_skb = j1939_session_skb_get(session); struct sk_buff *skb; int ret; @@ -1015,8 +1030,10 @@ static int j1939_simple_txnext(struct j1 return 0; skb = skb_clone(se_skb, GFP_ATOMIC); - if (!skb) - return -ENOMEM; + if (!skb) { + ret = -ENOMEM; + goto out_free; + } can_skb_set_owner(skb, se_skb->sk); @@ -1024,12 +1041,18 @@ static int j1939_simple_txnext(struct j1 ret = j1939_send_one(priv, skb); if (ret) - return ret; + goto out_free; j1939_sk_errqueue(session, J1939_ERRQUEUE_SCHED); j1939_sk_queue_activate_next(session); - return 0; + out_free: + if (ret) + kfree_skb(se_skb); + else + consume_skb(se_skb); + + return ret; } static bool j1939_session_deactivate_locked(struct j1939_session *session) @@ -1170,9 +1193,10 @@ static void j1939_session_completed(stru struct sk_buff *skb; if (!session->transmission) { - skb = j1939_session_skb_find(session); + skb = j1939_session_skb_get(session); /* distribute among j1939 receivers */ j1939_sk_recv(session->priv, skb); + consume_skb(skb); } j1939_session_deactivate_activate_next(session); @@ -1744,7 +1768,7 @@ static void j1939_xtp_rx_dat_one(struct { struct j1939_priv *priv = session->priv; struct j1939_sk_buff_cb *skcb; - struct sk_buff *se_skb; + struct sk_buff *se_skb = NULL; const u8 *dat; u8 *tpdat; int offset; @@ -1786,7 +1810,7 @@ static void j1939_xtp_rx_dat_one(struct goto out_session_cancel; } - se_skb = j1939_session_skb_find_by_offset(session, packet * 7); + se_skb = j1939_session_skb_get_by_offset(session, packet * 7); if (!se_skb) { netdev_warn(priv->ndev, "%s: 0x%p: no skb found\n", __func__, session); @@ -1848,11 +1872,13 @@ static void j1939_xtp_rx_dat_one(struct j1939_tp_set_rxtimeout(session, 250); } session->last_cmd = 0xff; + consume_skb(se_skb); j1939_session_put(session); return; out_session_cancel: + kfree_skb(se_skb); j1939_session_timers_cancel(session); j1939_session_cancel(session, J1939_XTP_ABORT_FAULT); j1939_session_put(session);