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=1794273300; b=S7gPHqbdQm717/4oM67EWyKq96sj2WPRc8ZK1uppkpUW4PiqNidT5kq4sOabvWfa5CFJ Is/2dm4mZrKuoM+YospjzeJF63P58toEC7fTq/mrMKIP3/agOn4+tYKJBX7u3I7oyF75b j8g7K7CGYNoZ90+MseCXkK91hl2jz2nrq7f3WGv0ojmsFlNKf0QTBJi5Vu4AuZYlHO09q 8lMBy1kEk9dH4Tw7YnwFSIe0VOgFyjb7jJP8JEkbFCeeyV9S8LWokBKQBIeN+Mu5JD6wq FEjll/6h/9uXFvHxtDBbk2EGMODbKUeFK4l/0PiygpIosmPyrc4hIlNGwJdzEq6Ez7A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794273300; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=5eH0cVXHUvpBtQl/d4AtlDe2COkCokHmPTaR4pHauKI=; b=tsnwklWsftFtpN9nIgTUnMspN0i1tcuekgiNXgftUd0PMdIIhgvHHN0Ec7Su7Orajdwc dITNCtIC0yuhKbnNm9iFYlZxEV0vlrd7tJ2l06w5pwSfJirc5/Otb/W7hCXQprBRVRgV5 i9xDJGlyLc4qBpaOACZFmi5HSkLIPCVKE/i8bs3SjbUQtEW0bi7uQMZZt/SNMS9MKo5ug JCR91nL29RChon8Tbj5mpmQ/aNfRaM5/wJBzkuNLzZo60TsNA8kWETSlNbS4QssnxLtDP jBTDb0UqxxSXxGz6VrGhCs1dg4+CkgR38tmiWyjSrrK7iaA/sIpbjZdqmFkE4wS1vuA== 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=XeHu9Hud; 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 49CF2606A31C for ; Tue, 10 Nov 2026 01:15:00 +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=XeHu9Hud Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B8CA1F0089F; Tue, 10 Nov 2026 01:14:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794273300; bh=5eH0cVXHUvpBtQl/d4AtlDe2COkCokHmPTaR4pHauKI=; h=From:To:Cc:Subject:Date; b=XeHu9Hudkq8u36l2PAhaCgscWQjsU3oKbrTBtb7mEPSNRVGdhWKrQmy4FP7nzt6lc IDIRgcBq2gzEvhY2SKeJoC0yH4PQA5Y8d1I7CSyZ2ClYAKkaRXWOahK1x8oAs6Olwz Bw5MUtDzTyPiPDYTVFur9ObettohpKD2zlOEn+CBJrTNziWELyT7g/bw5VCXuL8/t0 r1fKZmhOTMmyD5mP64Y215a5+GztaQPac1M0B29cgDScBm9Sm4CNd8mBEyQU0BInWl jLsSsnD6BOQGPTgjj+L5MAa6T9n/clDGUz3fCc0iHgl902X0C346W6hFwIJbRNcKfJ PzlxQXvRkI9sQ== From: Sasha Levin To: zhaoyz24@mails.tsinghua.edu.cn, yangyx22@mails.tsinghua.edu.cn, wangao@seu.edu.cn, fengxw06@126.com, qli01@tsinghua.edu.cn, xuke@tsinghua.edu.cn, asmadeus@codewreck.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] 9p/xen: drain response work after unbinding IRQ" failed to apply to 6.1-stable tree Date: Mon, 9 Nov 2026 20:14:58 -0500 Message-ID: <20261109201458-failed-6.1-7b6f2e3c29fb@kernel.org> X-Mailer: git-send-email 2.53.0 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 7b6f2e3c29fb4d76f1e4973280792eabbd526602 # git commit -s git send-email --to '' --in-reply-to '20261109201458-failed-6.1-7b6f2e3c29fb@kernel.org' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 7b6f2e3c29fb4d76f1e4973280792eabbd526602 Mon Sep 17 00:00:00 2001 From: Yizhou Zhao Date: Tue, 9 Jun 2026 23:52:01 +0800 Subject: [PATCH] 9p/xen: drain response work after unbinding IRQ 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 --- 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 5a0b5b83e8ab4..9ee1ac9143d43 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -282,14 +282,14 @@ 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++) { grant_ref_t ref; -- 2.53.0