From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f198.google.com (mail-pl1-f198.google.com [209.85.214.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6529A435529 for ; Mon, 10 Aug 2026 18:09:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786385400; cv=none; b=CwsVFL+plmnRAyKMAShFM0Wxbko29OccRjTwDz+Db7ACPy3HwJZzBVb8fiojt5p/ObnSfbgPEnR5A00AKHgJwLWmyKs42IxVNYvWrebZiXl6ZuzsCBQX/t2HZQzjwF94DU/FJsm8H2jt3wdqbPKm3Kh7AEElF6SalhHXFcksUZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786385400; c=relaxed/simple; bh=x7tIsrbMyUPwgd1k03RHVrZSUrj+/5nLv/vrSIRF7kI=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=gqGbISchzuFGNUvNWaWBDL570meqHAaGFcX7Q4drQT3DEa119Z1nxOLHFpZFlNTL0aymx5B46DMRCzj74FVPxYqGxEzBLSISYuJKtv7D2J4RGcANoYV8f181816oBaWMd0m0/p42g9ib/qeADTwHyOFrXM1AsWHHzYc99zqjjeE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--almasrymina.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=e+upRU50; arc=none smtp.client-ip=209.85.214.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--almasrymina.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="e+upRU50" Received: by mail-pl1-f198.google.com with SMTP id d9443c01a7336-2cc6dd43737so52856015ad.2 for ; Mon, 10 Aug 2026 11:09:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1786385397; x=1786990197; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:mime-version:date:from :to:cc:subject:date:message-id:reply-to:content-type; bh=XKDruZQ0TN5xeCIrhjnVIOzXHZSGCKivlM0ICoimkCg=; b=e+upRU50eGGwmvtVtyt44gnQa71k0YE7umS8uosTmTkb3OZCkbNfLfQCRg6rcOKzKX 8mZsqzPAR7qBOBzxiRSj3w/zZTqeLVGWylfXfjGCR9HJE2rHAwLA9R8tjFajycIpGrGs dr6q1gfWSgNzobpP+VUdsWfGpvAepk/trfPH6Yj+D46ZymvV/T8mwXDbyBWF7oezEkrS Y9dzQbMrWIRZyiqw5ps9spcOaa57E6uCZ3X+bfD1Mb969Jve+9PY2U2cRUnQgn97Me7T mmSabipLYtCy7QWhhPEpKxWq9tHQMtGeX022hShuaC7yu4uXEwHQ6BU4ky0cCLJpUatL Pnsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786385397; x=1786990197; h=content-type:cc:to:from:subject:message-id:mime-version:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=XKDruZQ0TN5xeCIrhjnVIOzXHZSGCKivlM0ICoimkCg=; b=VIt1A2cCM4nvmdCzkYdh0CDUopgoVQcEiPLBILWU75ZA1hjsEUcnztu8NeBvi20y6i ythQ+zj0NT8U//tNMfdrVAweM9BhDAsX0wbYUhvUVKwxfFhVZ8gEUz3ViwClm7CCe7nV Qm3HE7H3byhyDc69ZWoNvBFONbYnEl/4Hn/MVqjowER4qJ3wWc7BTas6KtmTVdNqsJW6 OuGFc0ILo370ezPCNSE6y4QTAPhCIAtNoAgy+lQ1qpSjWPMm8IipISsyYUZNcABXiKQU ExATjTlShemu7W63LzYXxftlITOXYcLeUcfxtKNSNKIFFInuTucG4i5LhriHXM5pXavc jk+g== X-Gm-Message-State: AOJu0YwXLXcjL2WwpN8zPvMfFmcp2JfntNFWesPeyLYB/3v+nZ14bRQd VIp2Y95aIGthl0+yYFIAEo/GYCbv/in1Ia5+taMOZoI0qnLvX/ZAynYRvBzSYyC/ao3noQlSPSp jPhKSssSZYuhsJD4rZw4O91rbgxH+ztjbW4dlKOaZJy7K0Gvd4PQr1ebic79fjNXUNE9EN52she 5pSyAE9Ylm1YP0qZnSpPh+jk1ALZE/fxSQszLqNCuWPVjwLP/OW7+K5A2t00XX5uI= X-Received: from dycog4.prod.google.com ([2002:a05:7301:9a84:b0:313:cf74:cf85]) (user=almasrymina job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:d58e:b0:2c9:e835:ac67 with SMTP id d9443c01a7336-2d0caa03d1fmr563084775ad.19.1786385397137; Mon, 10 Aug 2026 11:09:57 -0700 (PDT) Date: Mon, 10 Aug 2026 18:09:43 +0000 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.679.g6767b8d81c-goog Message-ID: <20260810180956.2348280-1-almasrymina@google.com> Subject: [PATCH net v2 1/2] net: core: propagate unreadable flag in skb_zerocopy From: Mina Almasry To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, dev@openvswitch.org Cc: Mina Almasry , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Neal Cardwell , Kuniyuki Iwashima , Aaron Conole , Eelco Chaudron , Ilya Maximets , Jason Xing , Pavel Begunkov , Stanislav Fomichev , Bobby Eshleman , Florian Westphal Content-Type: text/plain; charset="UTF-8" skb_zerocopy() fails to propagate the unreadable flag when copying devmem fragments, causing target skbs to appear as readable memory. This patch fixes the flag propagation. Additionally, it returns -EFAULT if standard payload is mixed with unreadable devmem fragments during extraction, and clamps unreadable skb lengths in openvswitch queue_userspace_packet() to avert truncated invalid payloads. Fixes: 65249feb6b3d ("net: add support for skbs with unreadable frags") Cc: Pavel Begunkov Cc: Stanislav Fomichev Cc: Bobby Eshleman Cc: Florian Westphal Cc: Aaron Conole Cc: Eelco Chaudron Cc: Ilya Maximets Signed-off-by: Mina Almasry Reviewed-by: Pavel Begunkov --- v2: - Return -EFAULT when mixing unreadable and readable frags (Pavel). - Clamp unreadable skb lengths for openvswitch queue drops (sashiko). v1: https://lore.kernel.org/r/20260801125308.1342897-1-almasrymina@google.com Openvswitch maintainers: PTAL at the openvswitch changes closely. They are reported by sashiko as an also-need part of this fix: https://sashiko.dev/#/patchset/20260706155219.23757-1-fw%40strlen.de --- net/core/skbuff.c | 13 ++++++++++++- net/openvswitch/datapath.c | 2 ++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index ba3dbac80fb49..d21af68156950 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3870,7 +3870,8 @@ EXPORT_SYMBOL_GPL(skb_zerocopy_headlen); * Return value: * 0: everything is OK * -ENOMEM: couldn't orphan frags of @from due to lack of memory - * -EFAULT: skb_copy_bits() found some problem with skb geometry + * -EFAULT: skb_copy_bits() found some problem with skb geometry, or readable head + * payload would be mixed with unreadable frags. */ int skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen) @@ -3905,10 +3906,17 @@ skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen) } } + if (!skb_frags_readable(from) && j > 0 && len) { + put_page(virt_to_head_page(from->head)); + return -EFAULT; + } + skb_len_add(to, len + plen); if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) { skb_tx_error(from); + if (j > 0) + put_page(virt_to_head_page(from->head)); return -ENOMEM; } skb_zerocopy_clone(to, from, GFP_ATOMIC); @@ -3928,6 +3936,9 @@ skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen) } skb_shinfo(to)->nr_frags = j; + if (i > 0 && from->unreadable) + to->unreadable = 1; + return 0; } EXPORT_SYMBOL_GPL(skb_zerocopy); diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c index ae69b2cabab9e..7c663d7846174 100644 --- a/net/openvswitch/datapath.c +++ b/net/openvswitch/datapath.c @@ -480,6 +480,8 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb, } skb_len = min(skb->len, cutlen); + if (!skb_frags_readable(skb)) + skb_len = min_t(size_t, skb_len, skb_headlen(skb)); if (nla_attr_size(skb_len) > USHRT_MAX) { err = -EFBIG; goto out; base-commit: dd057113ac7ba5bdd2aed3d9405305911152f911 -- 2.55.0.679.g6767b8d81c-goog