From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f169.google.com (mail-pg1-f169.google.com [209.85.215.169]) (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 33A53192B75 for ; Mon, 20 Apr 2026 08:28:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.169 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776673717; cv=none; b=doh8jAMXmOgT+eaoPKZ/RsIpkRpXjzCYwvXmvdBSvK/mC9kC9X+y80bH54J9nOCZ0PPF3+YTROc2hanI7hjuMIlTbMcxigov7FDM/xMpoHJjCf2y4+UF1XDriWI1qz/d1YHVIo6bx4PSNBjoQya4ri1zGaoG1nBe3vci+SGNFzA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776673717; c=relaxed/simple; bh=yPn3zWFs108M5RNr5Rp+kEd1EJ6GP6gcs1NhsUwltNo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=XTWORYwC5CVdfotS0YV0tqqTjear7Wcs7TJmpUwQPDpZxQfNNOIMhreu9uXhlFE0gzduzCxmXWwiKPmNgSZkwnKN6uMBSNHdkoZWEmAeo8TYZhXWkk00IdKUvMbm1ZqbtARgSWLbRauIaYhCCi6tK4N3XqXnlbPiujF5SPfeL80= 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=G4CV6+1Q; arc=none smtp.client-ip=209.85.215.169 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="G4CV6+1Q" Received: by mail-pg1-f169.google.com with SMTP id 41be03b00d2f7-c76b994f7a8so827468a12.3 for ; Mon, 20 Apr 2026 01:28:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1776673716; x=1777278516; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=xyOE2AqceayWh7ep8Gr2jA+i1jYVD1CfxeHKydIjAYY=; b=G4CV6+1Q32THKkGhFJhlBksIHOw0inSPbLhegtWHakTCisYxra7qTYhgXrlmtzwR1K I7G9qMhxrYrQzIXvOJofo49gc2NuLuD+3NiUIf2oFFvPmlW9WZBEfXOo5NQWuhbEOqNA EGap4FYSikfzDhSZwSaSzlJH665LgTwvrR0SeV5Klps1ukMfRNgHO23BKX+uymCnHeII Jiggd7F7p3uDMrxMAIQzpJ5jmDf/SflTDLNeeWDnpEw8Iy8pJSYCHVA019UQZV0k2kvP aCjFH57pdRP7bw7cPVXzeFpl0hZofcIEHrRo3YW9/GKCCcS1vi6oCgUa6AE6o2t43iGE quAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776673716; x=1777278516; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=xyOE2AqceayWh7ep8Gr2jA+i1jYVD1CfxeHKydIjAYY=; b=plCJEAkh3VXuRY2Q46Oohr1w95gst6318jetmO2GVFEvxxqJTz7Ma2zsZp+dm7lmzA jEazLPjsA7dTXEVbWXzD72GMFu4uZkCDYpmmuXtGivFb1sOgIpMMgVfT9h3zffxuccUc mB0M4NH9hifIcSQwvJJ0keCLFyJ9nbhbEdMiTh6Pbahj/BkR4xZCznsRXjGEe8+OXv4M aGpnlRL2663w6W1U69N+ySy3S+fbfFZNQjeer7HhKmzN21VvrFEW5A0JsFP4is3QYd4E xeTtxXaj3qbUdun4LlUZLJjkCTOomYmUqUef2u21qp7GX+bdwpcx+2ClOkkTozbojru0 cj9Q== X-Gm-Message-State: AOJu0YysM94hykCYMtq49Wow9R3CHfojBjaYPe+kbCopg0rZ6bsANYD2 +2ilCFU3XMT6+AwqmdUq6mRoXyrnMJWZZhTtVNB9h09y1yKoTUNXgq1d X-Gm-Gg: AeBDietRvtlahFh+TrNm+p2KPfouFamReoyprpAwsBTlyhqsQms1iBUn94utKG5DrIB MpakjPakFF7A8Pk3lTWYlkNhTtxGVWeFxuSEvl/gH5zho6qRut5rLIXrCXFHmzNLyObzSpVi1PU EbjbYc/T1bSdIEuo+WAR26elrBCDNNVfO6d3Jt11ajWF0XJOEnJU9aznfm4MSPydLQyoC+pz/Nh oQlUKz7q+k/Ou9ThZLoxtQ4pT27c4nXaZDe9az3DZnt7Ifz26yo/D2L7+ZC7IjsdFtbg0cTvsp3 9RtglSbXCMPfMuAz8nXpO0wfPgeU+QvKjhxXxb9TnxrvlFMHHhPjg4U8ORfL5qVkWaozhlkp56F /FWhi6IVB0hSA1SZxeXPML7yTiymFgdTpNwB8vxCQfKU5t1KJ52+IW9cnsALNUkXvcxW9/mwjrT KuiwE89gqtGXwM8N3OCig8mWq0SH+9Ks9PbtOB11k2Dm6GqNgloOSJnD3MpV0Yb3ZgneuwCIGlT hWoLVjP X-Received: by 2002:a05:6a20:7285:b0:39b:e321:67ea with SMTP id adf61e73a8af0-3a08d8fba25mr13642856637.45.1776673715599; Mon, 20 Apr 2026 01:28:35 -0700 (PDT) Received: from KERNELXING-MB0.tencent.com ([43.132.141.20]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c798b56a758sm1728010a12.18.2026.04.20.01.28.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 01:28:34 -0700 (PDT) From: Jason Xing To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, sdf@fomichev.me, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Subject: [PATCH net v2 4/8] xsk: prevent CQ desync when freeing half-built skbs in xsk_build_skb() Date: Mon, 20 Apr 2026 16:28:01 +0800 Message-Id: <20260420082805.14844-5-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20260420082805.14844-1-kerneljasonxing@gmail.com> References: <20260420082805.14844-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jason Xing Once xsk_skb_init_misc() has been called on an skb, its destructor is set to xsk_destruct_skb(), which submits the descriptor address(es) to the completion queue and advances the CQ producer. If such an skb is subsequently freed via kfree_skb() along an error path - before the skb has ever been handed to the driver - the destructor still runs and submits a bogus, half-initialized address to the CQ. Introduce a new common helper to fix the issue. That function will be used by the subsequent patches soon. Closes: https://lore.kernel.org/all/20260419045822.843BFC2BCAF@smtp.kernel.org/ Fixes: c30d084960cf ("xsk: avoid overwriting skb fields for multi-buffer traffic") Signed-off-by: Jason Xing --- net/xdp/xsk.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 4fdd1a45a9bd..614e7bd1252b 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -717,6 +717,12 @@ static int xsk_skb_metadata(struct sk_buff *skb, void *buffer, return 0; } +static void xsk_drop_untrans_skb(struct sk_buff *skb) +{ + skb->destructor = sock_wfree; + kfree_skb(skb); +} + static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, struct xdp_desc *desc) { @@ -890,7 +896,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, free_err: if (skb && !xs->skb && !skb_shinfo(skb)->nr_frags) - kfree_skb(skb); + xsk_drop_untrans_skb(skb); if (err == -EOVERFLOW) { if (xs->skb) { -- 2.41.3