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=1794440880; b=uik6WIJt4bp8tMsw27P2+nEeY9knzbIfDng2nE08Nf7bvZS4kV5LE4luV4m2gWUo8qoF hcRtHHuXt1tWktT04SzsdcpqzrYb/+FvSmJCs310soSdLX51HDasE/iLzqsJn8e3vSQHh 81iTdcphm8op7v8V6bnbOGdw8jHz7VEFBAXEKvHzN7UZ4ByPWMgDuMtYdazxeQ2IMu5PZ ZKxwYAAlHDfwhRECCyaadWyc08DiDvYA76aR9fpEUvsA6MXKVMkP3ntrrVT6UxFopfHup A9ryNFBLR3p8ySDyR5pIrn4dk8zpp2t/P97Nqd0OnF6sGsu6t6ubEWDzwEz4wuQYNQA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794440880; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=h+N9Abt0w/0DlLriHZkVT17Jo0tdw/y6Vn6fU1C3O1s=; b=riFZSpplQq3n7Iqvc9C9HDOQ0bPT95HeSZYbfZqrfAPcQzZfO7HBW7kqecvEYPniGN2T R4A1hecXi1YI7Zg84FbgiVkBZK1VBYJAgmdC+HzIOHpNkOkLEZnmDy7PUea0g1PRZwjrr Uzs7bImab1whm1+LyquJ/9zNHgl5ZIFnNePNlwKXnVjc74b1VZJUTv/k7GLjN5p7Aa43j ZiwTHYE2KjqNsSsg5fIrqdXyeAWV58kYKIGT+kPQpjRop5D5QXyAPLFsvK/J2mKxADb6G h34buWAvKIFq4KCwxXymgQMU4SysYrpKGMBjKTzYb6oGaBiHLADjlLdfy8hs/vZ4jJg== 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=co8p4ZIi; 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 C7DA4606A336 for ; Wed, 11 Nov 2026 23:48:00 +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=co8p4ZIi Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68EF71F00A05; Wed, 11 Nov 2026 23:47:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794440880; bh=h+N9Abt0w/0DlLriHZkVT17Jo0tdw/y6Vn6fU1C3O1s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=co8p4ZIiqao/0wh5dvwZ4esxMZ1TX9PqK3i+2g+k1lnbvruS0dnQZHSrjZQEbCOa2 AhNVcVwkzXWApeRMqLgZFEqTz9WuUDFHmKOtKp92kSYb+3GVq2MfM43h9mTkUmnj+B rWcMUglrWeYnZpv3t9WpVxG+CcL9acc2TXtzPDyp4aWhjM2WGs4BBBPGOqU38LdgOY 13l+FRhS3m/Om7DfMCg1fu7pSRFhvwf9NsiPFM25ddXM6nJaAOTEC/X8erxzdECjLh LJcLDhxmuNZZJxRe5act57QVzKx+FNbZYt5Or6ats1Y99snsKMaMKOvZziWyjX9DIu ShOODEuObyqtQ== 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 6.6.y] 9p/xen: drain response work after unbinding IRQ Date: Wed, 11 Nov 2026 18:47:58 -0500 Message-ID: <20261111234750.833665-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109201020-failed-6.6-7b6f2e3c29fb@kernel.org> References: <20261109201020-failed-6.6-7b6f2e3c29fb@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 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 ee5bbdf7dec25..fbf8e6598f273 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -289,12 +289,12 @@ static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) for (i = 0; i < priv->num_rings; i++) { struct xen_9pfs_dataring *ring = &priv->rings[i]; - cancel_work_sync(&ring->work); - if (!priv->rings[i].intf) break; if (priv->rings[i].irq > 0) unbind_from_irqhandler(priv->rings[i].irq, ring); + cancel_work_sync(&ring->work); + if (priv->rings[i].data.in) { for (j = 0; j < (1 << priv->rings[i].intf->ring_order); -- 2.53.0