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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 6D2BEC3A5A1 for ; Thu, 22 Aug 2019 19:12:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2EE0323400 for ; Thu, 22 Aug 2019 19:12:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403894AbfHVTMJ (ORCPT ); Thu, 22 Aug 2019 15:12:09 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:47444 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726142AbfHVTMI (ORCPT ); Thu, 22 Aug 2019 15:12:08 -0400 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::d71]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 66853153410DC; Thu, 22 Aug 2019 12:12:08 -0700 (PDT) Date: Thu, 22 Aug 2019 12:12:07 -0700 (PDT) Message-Id: <20190822.121207.731320146177703787.davem@davemloft.net> To: dhowells@redhat.com Cc: netdev@vger.kernel.org, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net 0/9] rxrpc: Fix use of skb_cow_data() From: David Miller In-Reply-To: <156647655350.10908.12081183247715153431.stgit@warthog.procyon.org.uk> References: <156647655350.10908.12081183247715153431.stgit@warthog.procyon.org.uk> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 22 Aug 2019 12:12:08 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: David Howells Date: Thu, 22 Aug 2019 13:22:33 +0100 > Here's a series of patches that fixes the use of skb_cow_data() in rxrpc. > The problem is that skb_cow_data() indirectly requires that the maximum > usage count on an sk_buff be 1, and it may generate an assertion failure in > pskb_expand_head() if not. It sounds like you are effectively doing a late unshare when you have to do in-place encryption. Why don't you just do an skb_unshare() at the beginning when you know that you'll need to do that?