From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f177.google.com (mail-dy1-f177.google.com [74.125.82.177]) (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 C907734AAF2 for ; Wed, 20 May 2026 16:00:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779292841; cv=none; b=GBF48cqokk+ZWm+jDxNKwAq5I5DldKHZdZsqHoTpKRAdrQpjeBtF9t5jml3drVp3N7gJ+zYb7hDiq7ufeNtOnIGqUn1PMkALgdGkXR9YxkrLS+iAAO1zD/b6J7UNBXZwINov7GIIgV3JV5y+NOrvNq4s8jVRJg6bl1OZeDv3z/U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779292841; c=relaxed/simple; bh=EYJENH/E9aIT1O7dcWbTzgwVXLLggCk/JlwRe3Mgr6g=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=L+7eM2ZUxx1QzIgUnM7vNTXQFbCzAU2dpCgdLohspatPEou3FP/ouw+uXEvLNnKiIYtuj8QKVoi8KOFfpjuxwhM1dMaKTOcsD4jzwuUJhV0Wz1xM9iT15OPt6I9ffjD3tx7qcSgr3dQZ3LEhoIGHsR7lLR35T2i841Y2Q14BRQk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=r5P7wyPD; arc=none smtp.client-ip=74.125.82.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="r5P7wyPD" Received: by mail-dy1-f177.google.com with SMTP id 5a478bee46e88-3042a388168so74049eec.1 for ; Wed, 20 May 2026 09:00:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779292838; x=1779897638; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=jZJSUSn4qvTX086pa/Fy4nlh1Sgz6dj9ak0JISPiC70=; b=r5P7wyPD6ZOmqH5FIN6WC+P/QqQS/6J+jyST9QbYyJHqMw22PfKiua8mAA+SPgTW0/ oCXwfS2nPIId7QC4OungYlSzZRL350SHj1hTj77OVnolHHBE+EHEzC+c81M5faW+6KTm mfDczGPIZdabk2QxCdIxal5ucqTZjB6O88cXWif1P8H10gcxa1Bi/DxAsTQj/4RMMsi3 w4TDEab5jFmPWBf8d4qb7PTyCXBEGQSB82fQhK9GVQoam0oTsGKmBqtbEI62KZl2DYkf J1djl/Pm7xwj0Ocjbkg4/HGKOH/MecdtivKRMQssQRlGrgmkGoH3BVpbUuGL9QxpUuSC JS3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779292838; x=1779897638; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=jZJSUSn4qvTX086pa/Fy4nlh1Sgz6dj9ak0JISPiC70=; b=JZDlFM1DvWBv61UBRshfQE9/8tmnWb6zLJ4oqr1aRpZ9WAdh9b0USmvT1knsQFusYD 7SiDJzZAeaeyBpYHUkb8UhkvFit4do9WZ1Pyvllyr8Ua5G6S2f9eVNPrfButEtMNQ42e ZfxTqgZ+EYhc0I5/aKFezyqm8KvAHQlhBFSJNi9iOhoD22eeQQVkk5oAKXsAp3JvELtO uHemaWXAAejcUsL50/Q0FVdZtBy0lzoeGTIIX9qZsSmF98tz27koaj58seJ7kyLQARzC P/cj1dWGwUwBkqtUfnbDCWgbpSuMDWhgvuY/n6l4qhtmZriBsMXJzZpY7MA2phX7w8xK J6Ew== X-Gm-Message-State: AOJu0YyBNoBXd3nL4VypiXx/fXM/mqowLNpshrTpr7iimtzNDP8UFf+B aQXgH8B1MpoqR9GIvbdYKx1B6ldZkM0pJ01mNMSLvqyJ8wnWUW8ZXdK59NvD8Nt5 X-Gm-Gg: Acq92OGlgaTrf3kg2j5AGeB31oyQFReYIYevOp8LkRssi/ch9abT622OeaaoFiAFPcV 5aP5yk7z8YbL9p20y3jityGGo3RRPSRrOxM9pi6/F1OieRG+mdMZ0nPRGwdrikqQ4IW73LPJFyD vkHTCLQSPC3PjzRKlMxx+TcIKg87pKzUuxF8mL3dHfZOchMTynN7ccX3qKPOlHH070Jek+ZQzwx 3v1tXByiL4Fn8uk/FLviM45ZxySl/VIZCZGuc6wKTNeo4GWCdquU3WA6hlQgCRJu6owQt8rnO/Y 3kC5cDvM+Ja5fDx11lC8jrcLlb8qsVoRdOO6081dCymsLuRWLhBRgBM5Q7sk6MB/6qW59wOX2dD u6iUf6uHR5yaSqGNlrF1YopyWhTLD8kbuSdhZUCghksug71qIGlxGPsg40DiqTA3Fg9BLZ0B3mF 1umUkuBD85e005cBOQWdRdv4mLVVSoCjE8ti86zovzF+aU22DKPOLBOqneMJTDkC2oLrF4bGG/c Yb/RMA= X-Received: by 2002:a05:7300:430d:b0:2d9:db50:c6ce with SMTP id 5a478bee46e88-3042b30f58emr63273eec.3.1779292838345; Wed, 20 May 2026 09:00:38 -0700 (PDT) Received: from fx.tailc0aff1.ts.net ([206.206.192.132]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30296dcb6e9sm23412317eec.16.2026.05.20.09.00.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 May 2026 09:00:37 -0700 (PDT) From: Weiming Shi To: netdev@vger.kernel.org Cc: willemdebruijn.kernel@gmail.com, jasowang@redhat.com, pabeni@redhat.com, kuba@kernel.org, edumazet@google.com, dongli.zhang@oracle.com, xmei5@asu.edu, linux-kernel@vger.kernel.org, Weiming Shi Subject: [PATCH net] tun: free page on short-frame rejection in tun_xdp_one() Date: Wed, 20 May 2026 09:00:21 -0700 Message-ID: <20260520160020.375349-2-bestswngs@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit tun_xdp_one() returns -EINVAL on a frame shorter than ETH_HLEN without freeing the page that vhost_net_build_xdp() allocated for it. tun_sendmsg() discards that -EINVAL and still returns total_len, so vhost_tx_batch() takes the success path and never frees the page; each short frame in a batch leaks one page-frag chunk. A local process that can open /dev/net/tun and /dev/vhost-net can hit this path: it attaches a tun/tap device as the vhost-net backend and feeds TX descriptors whose length minus the virtio-net header is below ETH_HLEN. Each kick leaks the page-frag chunks for that batch, and a tight submission loop exhausts host memory and triggers an OOM panic. Free the page before returning -EINVAL, matching the XDP-program error path in the same function. Fixes: 049584807f1d ("tun: add missing verification for short frame") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Weiming Shi --- drivers/net/tun.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index b183189f1853..f594360d66d6 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -2394,8 +2394,10 @@ static int tun_xdp_one(struct tun_struct *tun, bool skb_xdp = false; struct page *page; - if (unlikely(datasize < ETH_HLEN)) + if (unlikely(datasize < ETH_HLEN)) { + put_page(virt_to_head_page(xdp->data)); return -EINVAL; + } xdp_prog = rcu_dereference(tun->xdp_prog); if (xdp_prog) { -- 2.43.0