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=-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 2C3EEC388F9 for ; Sat, 31 Oct 2020 11:42:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE78320825 for ; Sat, 31 Oct 2020 11:42:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144521; bh=owFw9jy5wvXy7h/hS8+rijyv14Ko20ItMZf4qlDxZW8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=pWHb9bCwCKX43L3UbvfyIfDkHz+xaaVtaruW4RHVn4EZA/eMkGwIOXKRTcSLB/1Ci sEAFA05EWkUm3NZMhYlcSCoWNrdUxDtAloi4sB+otjJYt8QzcR40Y02fTD9QjXNOe1 rfItQItTsTlfioBbj7asdrkH9KBq1r0ufyNABTRQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727794AbgJaLl7 (ORCPT ); Sat, 31 Oct 2020 07:41:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:41222 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727767AbgJaLl4 (ORCPT ); Sat, 31 Oct 2020 07:41:56 -0400 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 ED2C520719; Sat, 31 Oct 2020 11:41:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144515; bh=owFw9jy5wvXy7h/hS8+rijyv14Ko20ItMZf4qlDxZW8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eU7jqDDRwF1uxu0cT7FdoGVTbHe1AzqnPZDCLHQ9y8pZFJYmuJaeBSCrdFBP/toHT kriisNjC44k7r8FCyiB+U7exL3wsriQ0h9ZHVq5Ok2nKeEhzmY8i7i4XmHj+Bj+DSz 7FyLptvYsCqSUYb9cOasqTUz2t63d4ZcqbL4xMR4= 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 5.8 47/70] tipc: fix memory leak caused by tipc_buf_append() Date: Sat, 31 Oct 2020 12:36:19 +0100 Message-Id: <20201031113501.751220303@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201031113459.481803250@linuxfoundation.org> References: <20201031113459.481803250@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: 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 @@ -150,12 +150,11 @@ 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) {