From patchwork Sun Aug 29 12:59:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vasily Averin X-Patchwork-Id: 504238 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=-17.2 required=3.0 tests=BAYES_00,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_SANE_1 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 53021C4320E for ; Sun, 29 Aug 2021 13:00:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3192260F35 for ; Sun, 29 Aug 2021 13:00:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235352AbhH2NA4 (ORCPT ); Sun, 29 Aug 2021 09:00:56 -0400 Received: from relay.sw.ru ([185.231.240.75]:49042 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235271AbhH2NAz (ORCPT ); Sun, 29 Aug 2021 09:00:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=Content-Type:MIME-Version:Date:Message-ID:Subject :From; bh=8K7FRhFmUut9BDtM0WSDlvm2R6R2V2gQI8Js6NhL0YA=; b=PivL+U5CpIgSawX8jJX U+bbFpFJebnNS+4GLt/FQuWxz7Iw3p+ZqFhBh6HWGDPRb8a4bw/U8sdW3m/OOjwgg2ztSy+vEHy5V dBPK7wn1jcoVw03Fryd9neeX3G0/xmLNOoPFFNdzqdB5RtNZhwVinlbwEFoMtchqAvho2+eipQc=; Received: from [10.93.0.56] by relay.sw.ru with esmtp (Exim 4.94.2) (envelope-from ) id 1mKKPl-0007Us-2K; Sun, 29 Aug 2021 15:59:57 +0300 From: Vasily Averin Subject: [PATCH v2] skb_expand_head() adjust skb->truesize incorrectly To: Christoph Paasch , Eric Dumazet , "David S. Miller" Cc: Hideaki YOSHIFUJI , David Ahern , Jakub Kicinski , netdev , linux-kernel@vger.kernel.org, kernel@openvz.org, Julian Wiedmann References: Message-ID: <860513d5-fd02-832b-1c4c-ea2b17477d76@virtuozzo.com> Date: Sun, 29 Aug 2021 15:59:56 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Christoph Paasch reports [1] about incorrect skb->truesize after skb_expand_head() call in ip6_xmit. This may happen because of two reasons: - skb_set_owner_w() for newly cloned skb is called too early, before pskb_expand_head() where truesize is adjusted for (!skb-sk) case. - pskb_expand_head() does not adjust truesize in (skb->sk) case. In this case sk->sk_wmem_alloc should be adjusted too. [1] https://lkml.org/lkml/2021/8/20/1082 Reported-by: Christoph Paasch Signed-off-by: Vasily Averin --- v2: based on patch version from Eric Dumazet, added __pskb_expand_head() function, which can be forced to adjust skb->truesize and sk->sk_wmem_alloc. --- net/core/skbuff.c | 43 +++++++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 14 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index f931176..4691023 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1681,10 +1681,10 @@ struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom, * reloaded after call to this function. */ -int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, - gfp_t gfp_mask) +static int __pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, + gfp_t gfp_mask, bool update_truesize) { - int i, osize = skb_end_offset(skb); + int delta, i, osize = skb_end_offset(skb); int size = osize + nhead + ntail; long off; u8 *data; @@ -1756,9 +1756,13 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, * For the moment, we really care of rx path, or * when skb is orphaned (not attached to a socket). */ - if (!skb->sk || skb->destructor == sock_edemux) - skb->truesize += size - osize; - + delta = size - osize; + if (!skb->sk || skb->destructor == sock_edemux) { + skb->truesize += delta; + } else if (update_truesize) { + refcount_add(delta, &skb->sk->sk_wmem_alloc); + skb->truesize += delta; + } return 0; nofrags: @@ -1766,6 +1770,12 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, nodata: return -ENOMEM; } + +int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, + gfp_t gfp_mask) +{ + return __pskb_expand_head(skb, nhead, ntail, gfp_mask, false); +} EXPORT_SYMBOL(pskb_expand_head); /* Make private copy of skb with writable head and some headroom */ @@ -1804,28 +1814,33 @@ struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom) struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom) { int delta = headroom - skb_headroom(skb); + struct sk_buff *oskb = NULL; if (WARN_ONCE(delta <= 0, "%s is expecting an increase in the headroom", __func__)) return skb; + delta = SKB_DATA_ALIGN(delta); /* pskb_expand_head() might crash, if skb is shared */ if (skb_shared(skb)) { struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC); - if (likely(nskb)) { - if (skb->sk) - skb_set_owner_w(nskb, skb->sk); - consume_skb(skb); - } else { + if (unlikely(!nskb)) { kfree_skb(skb); + return NULL; } + oskb = skb; skb = nskb; } - if (skb && - pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) { + if (__pskb_expand_head(skb, delta, 0, GFP_ATOMIC, true)) { kfree_skb(skb); - skb = NULL; + kfree_skb(oskb); + return NULL; + } + if (oskb) { + if (oskb->sk) + skb_set_owner_w(skb, oskb->sk); + consume_skb(oskb); } return skb; }