From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.secunet.com (mx1.secunet.com [62.96.220.36]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 742993AB482; Wed, 3 Jun 2026 10:58:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.96.220.36 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780484290; cv=none; b=ZBteQd+1hsE20P0NeXucYUH/PH5BD109n23zZ8pCarGfLa/5OADI4W/qG9O1oRj/WojJmxwifV0f84zDiXV095tIA2771ton+iKgRZgKIcn1gl/Fr4CENeLxMkD2Rrn7cikHZ8M7f3503yChoVQC9Y854YBy7Ayp7URSlhO+Q90= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780484290; c=relaxed/simple; bh=kPDU3xfYprAjGu4n0CFmoBNElqvioUcz7b1ZVCVBhjE=; h=Date:From:To:CC:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=W3QACK5IHD/wOUNjpGUMtRSNd9SL6aRYxABpH0abRwe+Gmxs+Lc70Qni9bIxZ3MMq2UtWSe9fTfQ0WqU5CpT6rFt2QyQVVH9pwFfIxj3kolzx6nnX4GMeFFOMHQ8l+9xysvEOoYNEo+Bpus/7o8nbQBeU8mHCjZ5g9DINqg2JZE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=secunet.com; spf=pass smtp.mailfrom=secunet.com; dkim=pass (2048-bit key) header.d=secunet.com header.i=@secunet.com header.b=l1jlTbwA; arc=none smtp.client-ip=62.96.220.36 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=secunet.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=secunet.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=secunet.com header.i=@secunet.com header.b="l1jlTbwA" Received: from localhost (localhost [127.0.0.1]) by mx1.secunet.com (Postfix) with ESMTP id AD43D201E4; Wed, 3 Jun 2026 12:58:06 +0200 (CEST) X-Virus-Scanned: by secunet Received: from mx1.secunet.com ([127.0.0.1]) by localhost (mx1.secunet.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5199KdRImnJU; Wed, 3 Jun 2026 12:58:06 +0200 (CEST) Received: from EXCH-01.secunet.de (rl1.secunet.de [10.32.0.231]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.secunet.com (Postfix) with ESMTPS id F0E3020185; Wed, 3 Jun 2026 12:58:05 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.secunet.com F0E3020185 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=secunet.com; s=202301; t=1780484286; bh=88vfyAI5BxlYrHH4ipjrMq+DkRlkWfuHHgJg1xonYC0=; h=Date:From:To:CC:Subject:References:In-Reply-To:From; b=l1jlTbwAnSBJdefmwNF+5UnPZC+sSO/I7cRwi2iRQ+USK7moSihUldUct9FPx7v94 frL1ieLBeQ3H6o/P0af21cYUDhwApp0Nno3QLF+5EEJz7/OoSeW4gMz46k3WSj6pUX CzYAiW4QMpXzghblK9mPmFCrXjQS5IhF5936RA9LsUiDWjjp+F70NB2XYQCsIvegtB hYSd0+cgmHnavzEfvgThUmMJWuV2nq0EtSzn9r5OklahhtxoqPFpjPGdaZhuU3gXG7 i7sf7W7gnHkICd1awW6jOAhzLnWR7aj8eDE+/Zaj06Sy0jkef1Z5+st9f3kn0ueQQl ud9MAiiytaQ8A== Received: from secunet.com (10.182.7.193) by EXCH-01.secunet.de (10.32.0.171) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.37; Wed, 3 Jun 2026 12:58:05 +0200 Received: (nullmailer pid 1858503 invoked by uid 1000); Wed, 03 Jun 2026 10:58:05 -0000 Date: Wed, 3 Jun 2026 12:58:05 +0200 From: Steffen Klassert To: Alessandro Schino <7991aleschino@gmail.com> CC: , , , , Subject: Re: [PATCH ipsec] esp: fix page frag reference leak on skb_to_sgvec failure Message-ID: References: <20260601134526.82-1-7991aleschino@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260601134526.82-1-7991aleschino@gmail.com> X-ClientProxiedBy: EXCH-02.secunet.de (10.32.0.172) To EXCH-01.secunet.de (10.32.0.171) On Mon, Jun 01, 2026 at 03:45:25PM +0200, Alessandro Schino wrote: > In esp_output_tail(), when esp->inplace is false, the old skb page frags > are replaced with a new page from the xfrm page_frag cache. The source > scatterlist (sg) is built from the old frags before the replacement, and > esp_ssg_unref() is responsible for releasing the old page references > after the crypto operation completes. > > However, if the second skb_to_sgvec() call (which builds the destination > scatterlist from the new page) fails, the code jumps to error_free which > only calls kfree(tmp). The old page frag references captured in the > source scatterlist are never released: > > 1. sg[] is built from old frags via skb_to_sgvec() (no extra get_page) > 2. nr_frags is set to 1 and frag[0] is replaced with the new page > 3. Second skb_to_sgvec() fails -> goto error_free > > Fix this by adding a bool parameter to esp_ssg_unref() that, when true, > unconditionally unrefs the source scatterlist frags. Since req->src is > not yet initialized by aead_request_set_crypt() at the point of the > error, the source scatterlist is obtained directly via esp_req_sg(). > Existing callers pass false to preserve the original behavior. > > The same issue exists in both esp4 and esp6 as the code is identical. > > Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible") > Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible") > Signed-off-by: Alessandro Schino <7991aleschino@gmail.com> > --- > net/ipv4/esp4.c | 14 ++++++++------ > net/ipv6/esp6.c | 14 ++++++++------ > 2 files changed, 16 insertions(+), 12 deletions(-) > > diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c > index 513c8215c947..2429c7845984 100644 > --- a/net/ipv4/esp4.c > +++ b/net/ipv4/esp4.c > @@ -96,7 +96,7 @@ static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, > __alignof__(struct scatterlist)); > } > > -static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb) > +static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb, bool already_unref) > { > struct crypto_aead *aead = x->data; > int extralen = 0; > @@ -113,8 +113,8 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb) > /* Unref skb_frag_pages in the src scatterlist if necessary. > * Skip the first sg which comes from skb->data. > */ > - if (req->src != req->dst) > - for (sg = sg_next(req->src); sg; sg = sg_next(sg)) > + if (already_unref || req->src != req->dst) > + for (sg = sg_next(already_unref ? esp_req_sg(aead, req) : req->src); sg; sg = sg_next(sg)) > skb_page_unref(page_to_netmem(sg_page(sg)), > skb->pp_recycle); > } > @@ -220,7 +220,7 @@ static void esp_output_done(void *data, int err) > } > > tmp = ESP_SKB_CB(skb)->tmp; > - esp_ssg_unref(x, tmp, skb); > + esp_ssg_unref(x, tmp, skb, false); > kfree(tmp); > > if (xo && (xo->flags & XFRM_DEV_RESUME)) { > @@ -569,8 +569,10 @@ int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info * > err = skb_to_sgvec(skb, dsg, > (unsigned char *)esph - skb->data, > assoclen + ivlen + esp->clen + alen); > - if (unlikely(err < 0)) > + if (unlikely(err < 0)) { > + esp_ssg_unref(x, tmp, skb, true); > goto error_free; > + } > } > > if ((x->props.flags & XFRM_STATE_ESN)) > @@ -602,7 +604,7 @@ int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info * > } > > if (sg != dsg) > - esp_ssg_unref(x, tmp, skb); > + esp_ssg_unref(x, tmp, skb, false); > > if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP) > err = esp_output_tail_tcp(x, skb); > diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c > index 57481e423e59..50af6ab9b8fc 100644 > --- a/net/ipv6/esp6.c > +++ b/net/ipv6/esp6.c > @@ -113,7 +113,7 @@ static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead, > __alignof__(struct scatterlist)); > } > > -static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb) > +static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb, bool already_unref) > { > struct crypto_aead *aead = x->data; > int extralen = 0; > @@ -130,8 +130,8 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb) > /* Unref skb_frag_pages in the src scatterlist if necessary. > * Skip the first sg which comes from skb->data. > */ > - if (req->src != req->dst) > - for (sg = sg_next(req->src); sg; sg = sg_next(sg)) > + if (already_unref || req->src != req->dst) > + for (sg = sg_next(already_unref ? esp_req_sg(aead, req) : req->src); sg; sg = sg_next(sg)) > skb_page_unref(page_to_netmem(sg_page(sg)), > skb->pp_recycle); > } Now checkpatch complains about this: WARNING: line length of 106 exceeds 100 columns #21: FILE: net/ipv4/esp4.c:117: + for (sg = sg_next(already_unref ? esp_req_sg(aead, req) : req->src); sg; sg = sg_next(sg)) WARNING: line length of 106 exceeds 100 columns #75: FILE: net/ipv6/esp6.c:134: + for (sg = sg_next(already_unref ? esp_req_sg(aead, req) : req->src); sg; sg = sg_next(sg)) This is not a big issue, but it makes the code unreadable over time. Please check your patches before you send it.