From patchwork Mon Nov 9 12:53:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 322570 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 261B2C56201 for ; Mon, 9 Nov 2020 13:45:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDC33206ED for ; Mon, 9 Nov 2020 13:45:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604929502; bh=JLcEgLdL/kL4nRVPKC9wWdDIZP3QmaLJDeSXO5Gt35Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=iZS2BUPc47IpgW/lJ+iCKZl4DXtS/N1Uu311cXUmQj87Vu3+l/AWWzETRlZWeO2q+ FPZg/AcZJvB9NsLXz9NI2OC6ofkzmeJuLfBjz/mUxRUaLmsO4J2frEkEiLAqYIh8T0 I+M5xSio8PFUGR9th8jyYGyaTAXP4+Nq9PLrQ/Do= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730112AbgKINpB (ORCPT ); Mon, 9 Nov 2020 08:45:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:54366 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730411AbgKINAP (ORCPT ); Mon, 9 Nov 2020 08:00:15 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D02D1216C4; Mon, 9 Nov 2020 13:00:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604926814; bh=JLcEgLdL/kL4nRVPKC9wWdDIZP3QmaLJDeSXO5Gt35Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0Rt2mgqUr3CLe2BOK/uip1GEt2/Epr0+Yxwd02K6Nfe7X9NFhUjJUxyhLwAG9861M hKKfHodZDKGZnNPOzpdVObopMgo32hJCOrExtomfi4AIQnnOnElHNuMuTDrkT3eqjN 8at4/dKEIzDJbRkXbv5LVC/sV/r/zB0QFE4Emhew= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jon Maloy , Thang Hoang Ngo , Tung Nguyen , Xin Long , Cong Wang , Jakub Kicinski Subject: [PATCH 4.9 006/117] tipc: fix memory leak caused by tipc_buf_append() Date: Mon, 9 Nov 2020 13:53:52 +0100 Message-Id: <20201109125025.942325540@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125025.630721781@linuxfoundation.org> References: <20201109125025.630721781@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Tung Nguyen [ Upstream commit ceb1eb2fb609c88363e06618b8d4bbf7815a4e03 ] Commit ed42989eab57 ("tipc: fix the skb_unshare() in tipc_buf_append()") replaced skb_unshare() with skb_copy() to not reduce the data reference counter of the original skb intentionally. This is not the correct way to handle the cloned skb because it causes memory leak in 2 following cases: 1/ Sending multicast messages via broadcast link The original skb list is cloned to the local skb list for local destination. After that, the data reference counter of each skb in the original list has the value of 2. This causes each skb not to be freed after receiving ACK: tipc_link_advance_transmq() { ... /* release skb */ __skb_unlink(skb, &l->transmq); kfree_skb(skb); <-- memory exists after being freed } 2/ Sending multicast messages via replicast link Similar to the above case, each skb cannot be freed after purging the skb list: tipc_mcast_xmit() { ... __skb_queue_purge(pkts); <-- memory exists after being freed } This commit fixes this issue by using skb_unshare() instead. Besides, to avoid use-after-free error reported by KASAN, the pointer to the fragment is set to NULL before calling skb_unshare() to make sure that the original skb is not freed after freeing the fragment 2 times in case skb_unshare() returns NULL. Fixes: ed42989eab57 ("tipc: fix the skb_unshare() in tipc_buf_append()") Acked-by: Jon Maloy Reported-by: Thang Hoang Ngo Signed-off-by: Tung Nguyen Reviewed-by: Xin Long Acked-by: Cong Wang Link: https://lore.kernel.org/r/20201027032403.1823-1-tung.q.nguyen@dektech.com.au Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/tipc/msg.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -140,12 +140,11 @@ int tipc_buf_append(struct sk_buff **hea if (fragid == FIRST_FRAGMENT) { if (unlikely(head)) goto err; - if (skb_cloned(frag)) - frag = skb_copy(frag, GFP_ATOMIC); + *buf = NULL; + frag = skb_unshare(frag, GFP_ATOMIC); if (unlikely(!frag)) goto err; head = *headbuf = frag; - *buf = NULL; TIPC_SKB_CB(head)->tail = NULL; if (skb_is_nonlinear(head)) { skb_walk_frags(head, tail) {