From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793208858; b=pdvb+K3xB2aAxtmkJ5bywk5y2N+PMl0NRBXSvGsCXDU/T6nSDdSRWMyqbsbSJGlQ6jX8 y7prj5TfMIZQf32lfQGvevzy1FD6vUgwLC4xsqx3tyqN8coyT+Tsb4jczxzDokw2djjCr sCNetpiH5dKa8uEkwwkRdmldk+SPAgcBBJJnNYgiwqpP0AfzK+lLV6mBtNrSgPJiiKsFf B4e4T4so7GpGs0hyydEy+ow2SujLzJxdKW47jbc0NBzNYeQPdgolIjcdlbShqVVP+5naH wbgKMSxdIkWsT9qXkQUDSYnyiPJXrn8kKpr7hSa822Ge5aFqjA+SLh1iuOJLZoP2Wsg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793208858; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=VBLcKv2GDgrVjHl63ycKW7GhraXj0UQp+YBJnzEUJfI=; b=dazD26TILb4l93TcUVyVKGek0RVIbvYAefaWDwBjc5T+mzzBFafEBPPbpKzc3E3hxZ77 475LjBqNbBAQ5UcqokQIeANjKsaPLrHkftNWC29ZXA65OY8ipsta/MxKEcFnj9bX5vgHb Yx5H6WcTbCWYQHeN11BkpIGE/oKil+QsOKYflRqogzTPZrDqxE880kjoobaYYTs5NSY3A chW0p6XM10MdHUcngP5/EnsEx7VjgR4OjXZx8rLuum0i54cqbpvZXmqdmvOl3nnkWNLWM UL0+uZdf+u5F7oIb0QI3i8Zpc9bDrb028NxmiUDJ0rK7i1c0K1FpsxgcQ/YyjkeJOCQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=WYcbgfNi; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4C287606A31C; Wed, 28 Oct 2026 17:34:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=WYcbgfNi Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61C091F01825; Wed, 28 Oct 2026 17:34:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793208857; bh=VBLcKv2GDgrVjHl63ycKW7GhraXj0UQp+YBJnzEUJfI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=WYcbgfNirXsCPxhkCH5awAvCSCvPfRb4/YibobaFT7shzXhaeqiCRXtUFufJJ5k52 xtRh5Bh9Kq21PuoAOpcheFgTC1vit8v9GbrsydW8S/+C0oqjdOvfrolq62Ap2ktNo/ 2qLORqav9eerDmuNqvXWBPwpwjvHHrYWUdH8nf/A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josef Bacik , Jakub Kicinski Subject: [PATCH 5.10 266/516] xen/netfront: drop RX packets with a short Ethernet header Date: Wed, 28 Oct 2026 17:56:58 +0100 Message-ID: <20261028170009.792162016@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170003.522232767@linuxfoundation.org> References: <20261028170003.522232767@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josef Bacik commit 089e58805c452e52179482b1025a8e309a57f801 upstream. handle_incoming_queue() pulls pull_to bytes into the head before calling eth_type_trans(). pull_to is the length of the first RX slot, capped at RX_COPY_THRESHOLD, and that length comes from the backend. Nothing checks it against ETH_HLEN. If the first slot is shorter than ETH_HLEN and more slots follow, the head ends up shorter than an Ethernet header while skb->len is longer, and eth_type_trans() BUG()s in __skb_pull(). If the whole packet is shorter than ETH_HLEN, eth_type_trans() reads the header past the end of the data instead. Pull at least ETH_HLEN, and drop the packet if that fails, which also drops packets too short to hold an Ethernet header. This also checks the return value of the pull, which was ignored. Fixes: 0d160211965b ("xen: add virtual network device driver") Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik Link: https://patch.msgid.link/20261007-b4-xen-netfront-short-head-v1-1-12d7113a7e4e@toxicpanda.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/xen-netfront.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -1229,8 +1229,16 @@ static int handle_incoming_queue(struct while ((skb = __skb_dequeue(rxq)) != NULL) { int pull_to = NETFRONT_SKB_CB(skb)->pull_to; - if (pull_to > skb_headlen(skb)) - __pskb_pull_tail(skb, pull_to - skb_headlen(skb)); + /* pull_to comes from the first slot's length, which the + * backend controls. Make sure the head holds at least an + * Ethernet header for eth_type_trans(). + */ + if (!pskb_may_pull(skb, max(pull_to, ETH_HLEN))) { + kfree_skb(skb); + packets_dropped++; + queue->info->netdev->stats.rx_errors++; + continue; + } /* Ethernet work: Delayed to here as it peeks the header. */ skb->protocol = eth_type_trans(skb, queue->info->netdev);