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=1794049660; b=FZWAA9AIliZVUC3qLWx+SDFZeQ3sMpyCvGf+5AFtTassfW5c4NJDNW2Lxb57ErOY/sHA 73CQkIz7j84wDiQgVIPGqOEL0fNC0D3C1FkUM2t2Olnp7zMYV8iMyPRIGqsBkL0QhyACX Y2wus6gx0jAuwtZKYPxB/ThgbQuMc7wY9r4IGnKYNS9nopFvkzuh0kZx4uKEhsfGnCeS8 BizIIeujvgV50ThML3KctYcOK/3UvKcovmDwLMZlrKMzgHeMkAbBBj08rooQt6kd8JqY/ edgacUMqhTgEaH0+lqMI3GRZA0X5XlhEyPf4rMWrgNr/4dIoc8B2DjT/qjdagMSC7hg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794049660; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=fC/h8E3dpQLB3Pz4Pr7X/inJQjc3MJce0T5jvA5dgVQ=; b=Q+i0oj+nATS8D+xcPLUnIZEZixdW55024CCk3dCQI8BmelHhSR2UVac2n9QMYatoIzDt Sf9WmEygkXr6BHfeIBB8eTAebbLDzc0H7HSWv6Dnsh3q+zfe4gYQNC1ej/zBwPJXrkODS TJxdgiTCnzLq8LrHIIwsmQFb4lk8Qzcuej2YEeu07/petYLSYkUBcQSDla/mtxL7woLw8 il60fmpDKokdtq2TXfE8vhaR68FgNXi7O9AYZv3Dyb2oGPyGFSdIJwm4prL8qHlWWlkEP Bv3YOMdj+dGLD/IyfNKKDjCgFRfYwoPBVrVL+eacKlMOMmsq8k1RjuFUpMtP4Yygx/A== 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=F1tdxDEO; 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 56C89606A326 for ; Sat, 7 Nov 2026 11:07:40 +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=F1tdxDEO Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7751A1F0089F; Sat, 7 Nov 2026 11:07:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794049660; bh=fC/h8E3dpQLB3Pz4Pr7X/inJQjc3MJce0T5jvA5dgVQ=; h=From:To:Cc:Subject:Date; b=F1tdxDEOsS+aHSfz77LdlXb5IP4b+/UnPTqjHF4V2J2YCUTYRI3hw9SZsZlmwDBVB mjHcUoIADhCDCar6WdRMJyeNBqaQgN8m1pjwJ9taR2QA1acmhtSIQuBjNfZjox02Jo 7G6Qpi9z6LWIFw6jLyybk8H+R9xPe3w4FqvMMVFp7X77LtErDr9Fjf8ZLP775IygFR r1r8E1AGRy7zDXZ+x+gcxolBg6zvggyE/cpggI2Mtd7igKCRFCNeZcusPKggTQXQRl Ws2PXK7xcXBJB4v102zekOdiS7Ni+p/zWMUfDxlaT3kO18Ivf6NENPyagEb0bJYqL3 t/qX2U1BKRSRg== From: Sasha Levin To: fanwu01@zju.edu.cn, songl@zju.edu.cn, mszeredi@redhat.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] virtio_fs: read the vring size under virtio_fs_mutex in ->get_tree" failed to apply to 5.15-stable tree Date: Sat, 7 Nov 2026 06:07:38 -0500 Message-ID: <20261107060737-failed-5.15-e7ccc777a040@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 5.15-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-5.15.y git checkout FETCH_HEAD git cherry-pick -x e7ccc777a040343b80f95f4cc5c12ce1df3187f4 # git commit -s git send-email --to '' --in-reply-to '20261107060737-failed-5.15-e7ccc777a040@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From e7ccc777a040343b80f95f4cc5c12ce1df3187f4 Mon Sep 17 00:00:00 2001 From: Fan Wu Date: Tue, 22 Sep 2026 08:13:18 +0000 Subject: [PATCH] virtio_fs: read the vring size under virtio_fs_mutex in ->get_tree The vring size was read after virtio_fs_find_instance() had dropped virtio_fs_mutex, so a concurrent virtio_fs_remove() could free the virtqueue first. The reference from the lookup keeps the virtio_fs alive, but not its virtqueues. Hold the mutex across the lookup and the read. This issue was found by an in-house static analysis tool. Fixes: a7f0d7aab0b4 ("virtiofs: split requests that exceed virtqueue size") Cc: stable@vger.kernel.org Assisted-by: Codex:gpt-5.6 Co-developed-by: Song Li Signed-off-by: Song Li Signed-off-by: Fan Wu Signed-off-by: Miklos Szeredi --- fs/fuse/virtio_fs.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index 4f334766b8c30..674fd784cdb80 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -455,26 +455,23 @@ static int virtio_fs_add_instance(struct virtio_device *vdev, return ret; } -/* Return the virtio_fs with a given tag, or NULL */ +/* Return the virtio_fs with a given tag, or NULL. + * Callers hold virtio_fs_mutex, which also keeps the virtqueues alive. + */ static struct virtio_fs *virtio_fs_find_instance(const char *tag) { struct virtio_fs *fs; - mutex_lock(&virtio_fs_mutex); + lockdep_assert_held(&virtio_fs_mutex); list_for_each_entry(fs, &virtio_fs_instances, list) { if (strcmp(fs->tag, tag) == 0) { kobject_get(&fs->kobj); - goto found; + return fs; } } - fs = NULL; /* not found */ - -found: - mutex_unlock(&virtio_fs_mutex); - - return fs; + return NULL; /* not found */ } static void virtio_fs_free_devs(struct virtio_fs *fs) @@ -1700,13 +1697,17 @@ static int virtio_fs_get_tree(struct fs_context *fsc) * in chan->iq->priv. Once fuse_conn is going away, it calls ->put() * to drop the reference to this object. */ + mutex_lock(&virtio_fs_mutex); fs = virtio_fs_find_instance(fsc->source); + if (fs) + virtqueue_size = virtqueue_get_vring_size(fs->vqs[VQ_REQUEST].vq); + mutex_unlock(&virtio_fs_mutex); + if (!fs) { pr_info("virtio-fs: tag <%s> not found\n", fsc->source); return -EINVAL; } - virtqueue_size = virtqueue_get_vring_size(fs->vqs[VQ_REQUEST].vq); if (WARN_ON(virtqueue_size <= FUSE_HEADER_OVERHEAD)) goto out_err; -- 2.53.0