From patchwork Thu Jul 22 16:31:45 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 485148 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=-20.2 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, 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 0328EC63793 for ; Thu, 22 Jul 2021 16:51:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAC8161241 for ; Thu, 22 Jul 2021 16:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233609AbhGVQKu (ORCPT ); Thu, 22 Jul 2021 12:10:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:47916 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233500AbhGVQH1 (ORCPT ); Thu, 22 Jul 2021 12:07:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CAE2361D10; Thu, 22 Jul 2021 16:48:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626972481; bh=hp94ZkwBVS2jBmFpbc6jytE1/IwEUaY6GttH5hplepA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=I6nYlw1aZYStMbhDuEvQLI3LRrgITLCJlbtt4d75HCmE0EEFJL8pF0Xc+ilzU+3n7 wO85ylV5hxB7P51gAlHXstYvV2Glbn6Vx5gh4VYyuIhT1YdHmSwDvS2I9bydLLjRap xN9HbA7hNiRIO4uth7nLSH520xQiSZVLVnS/eRIk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Lobakin , Antoine Tenart , "David S. Miller" Subject: [PATCH 5.13 130/156] net: do not reuse skbuff allocated from skbuff_fclone_cache in the skb cache Date: Thu, 22 Jul 2021 18:31:45 +0200 Message-Id: <20210722155632.562876548@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210722155628.371356843@linuxfoundation.org> References: <20210722155628.371356843@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Antoine Tenart commit 28b34f01a73435a754956ebae826e728c03ffa38 upstream. Some socket buffers allocated in the fclone cache (in __alloc_skb) can end-up in the following path[1]: napi_skb_finish __kfree_skb_defer napi_skb_cache_put The issue is napi_skb_cache_put is not fclone friendly and will put those skbuff in the skb cache to be reused later, although this cache only expects skbuff allocated from skbuff_head_cache. When this happens the skbuff is eventually freed using the wrong origin cache, and we can see traces similar to: [ 1223.947534] cache_from_obj: Wrong slab cache. skbuff_head_cache but object is from skbuff_fclone_cache [ 1223.948895] WARNING: CPU: 3 PID: 0 at mm/slab.h:442 kmem_cache_free+0x251/0x3e0 [ 1223.950211] Modules linked in: [ 1223.950680] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.13.0+ #474 [ 1223.951587] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-3.fc34 04/01/2014 [ 1223.953060] RIP: 0010:kmem_cache_free+0x251/0x3e0 Leading sometimes to other memory related issues. Fix this by using __kfree_skb for fclone skbuff, similar to what is done the other place __kfree_skb_defer is called. [1] At least in setups using veth pairs and tunnels. Building a kernel with KASAN we can for example see packets allocated in sk_stream_alloc_skb hit the above path and later the issue arises when the skbuff is reused. Fixes: 9243adfc311a ("skbuff: queue NAPI_MERGED_FREE skbs into NAPI cache instead of freeing") Cc: Alexander Lobakin Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/dev.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6194,6 +6194,8 @@ static gro_result_t napi_skb_finish(stru case GRO_MERGED_FREE: if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD) napi_skb_free_stolen_head(skb); + else if (skb->fclone != SKB_FCLONE_UNAVAILABLE) + __kfree_skb(skb); else __kfree_skb_defer(skb); break;