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=1794439483; b=JFiaAtuBBHAjr/RW/KcJUduAOlv9nhQ5DorcnMyypzZ2dVI9mdGpJL8qHPMD4W70sXGp QXE+glgU8DsgehhZSwxDP/QkuyGATl6m1L0hqQy8tzB4U+EtVPfABaS4+qH9mC8L8+mjG roE4/bO2qwL2qEMhE7tkVvYfhmg8Zn9fN53/EkBujVB/4hJwDwjY3i7Q0Fm8+8iL+xicx 6dvN/4g82IMAPE/FKrO3EYegf9C5ldrfFMTeM9znBYftQbVhOKXewQfSJGgR4gYZjVHSL eY7RJYYJBrwSbed9cvFKk+lg0XibwGaaSubc7Mv7gmFhHEhtnFvNUrQ7m/QPAs6sgzg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794439483; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=0lZp5LYlWIljT/TDK+20V6m+qVZi6L43Se5nlTzzq3w=; b=dW1pMsitkhs/FmexIctORMhkMTvkj5k2KSDdK74rKk2H2g+9PvBZOoibBUGL4IcVw4sd C5dgVODh1OxYZLPQseHeDYJI/WZ7LBjkvDMJPxL2g1KLWfcyMNb9qaVjJM0Lq83vaCP3g cdZKX8oLmxS7xjdFrY7w6iPbRDHoUaMJ+jWs+EyKGkclg8nocHF9a7vAweX+Qp7SylXuW 5H05mTOR/qA7MKSvyE0el57aARPD3nIYdM483Mex8NKJxpftkOf3Uun6W3cnuxnyHsDWC ZeTSc01yuPHqk9Jv3Z73mgnvUCMf1+fXfmYztAdS7FLhiBwzLjd5M3tTBlCi/LZ7rJg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=MwHrruJT; 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 E9FA1606A321 for ; Wed, 11 Nov 2026 23:24:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=MwHrruJT Received: by smtp.kernel.org (Postfix) with ESMTPSA id 906CF1F00A05; Wed, 11 Nov 2026 23:24:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794439482; bh=0lZp5LYlWIljT/TDK+20V6m+qVZi6L43Se5nlTzzq3w=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MwHrruJTK0+6hY+BHccWcx7qtX/56Ab1lYWxYlxKhBbHPvvY97Z7DSh2668UrA5nm WCDNp5eQA33u9HRFK+uXniCTZ0bn90fwBYViH5FQ59tEmZ8iDL/UllaOZ5dzZKWZYe uYDIu3IdqoorsoOm6jDEf/0fIPeJqY9TQ2dv69eGQJZ7kGvr31QH3QnNFpyXDMBuLY rSFAaZZK0/Qf1pGzhKSIH8PebwCZL00O+KGa4takm0K40+qywTcNLcvwE7Kk7MBaN7 U8ysLao7CWwGmSEH73SOmbIPV8q9HeDTDhp8qaCpt1wyIi38bfMSdfdbKAsQoNLR1G uptt66JCFQsNg== From: Sasha Levin To: stable@vger.kernel.org Cc: Yizhou Zhao , Yuxiang Yang , Ao Wang , Xuewei Feng , Qi Li , Ke Xu , Dominique Martinet , Sasha Levin Subject: [PATCH 7.3.y] 9p/xen: drain response work after unbinding IRQ Date: Wed, 11 Nov 2026 18:24:40 -0500 Message-ID: <20261111232430.405441-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109200054-failed-7.3-7b6f2e3c29fb@kernel.org> References: <20261109200054-failed-7.3-7b6f2e3c29fb@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Yizhou Zhao [ Upstream commit 7b6f2e3c29fb4d76f1e4973280792eabbd526602 ] commit ea4f1009408e ("9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition") added cancel_work_sync() to keep xen_9pfs_front_free() from freeing a ring while p9_xen_response() is still running. The work is currently drained before the event channel IRQ is unbound. That leaves a race window where xen_9pfs_front_event_handler() can run after cancel_work_sync() returns and queue p9_xen_response() again. The following unbind_from_irqhandler() synchronizes with the IRQ handler, but it does not cancel work that the handler already queued. The teardown can then free the ring and private data while the response work remains pending, and the worker later dereferences ring->priv and priv->client. Unbind the event channel IRQ before draining the work. Once the IRQ is unbound, no new response work can be queued by the backend event channel, and cancel_work_sync() waits for any work that was queued before or during the unbind. It is then safe to release the ring resources. Fixes: ea4f1009408e ("9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition") Cc: stable@vger.kernel.org Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: GLM:GLM-5.1 Signed-off-by: Yizhou Zhao Message-ID: <20260609155202.1706-1-zhaoyz24@mails.tsinghua.edu.cn> Signed-off-by: Dominique Martinet [ sashal: Adjusted indentation to fit the existing if (priv->rings) cleanup wrapper for separately allocated rings. ] Signed-off-by: Sasha Levin --- net/9p/trans_xen.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index 71a4d276321e2..69a5129a9b64a 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -291,14 +291,14 @@ static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) for (i = 0; i < XEN_9PFS_NUM_RINGS; i++) { struct xen_9pfs_dataring *ring = &priv->rings[i]; - cancel_work_sync(&ring->work); - if (!ring->intf) break; if (ring->irq >= 0) { unbind_from_irqhandler(ring->irq, ring); ring->irq = -1; } + cancel_work_sync(&ring->work); + if (ring->data.in) { for (j = 0; j < (1 << ring->intf->ring_order); j++) { -- 2.53.0