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=1794063455; b=2SFYpT6Pe2m/x4t2dr8y3Gw0Piz6sbDqfFsE5AaHkz5PTOokVNzO2zcB8Wp+3yp7k/SG XWPBZ35iy8QayuY46RsaAcUkFfgzLqisMPXvgDK7x2deRlh3mXLyshqYqv9Xz75ZbGexK 1mWza2zFzlagHt2OSJbztz353TyBT64LyGaXI29ThA7vmQ0K9T/FViCAG0grHCEtdIP9W fmSjd6H68Y4ROs003mMl84wXVsCQJ3MxQTgfHPJrbF1+8MoqvYFP79BQ9bPa2L8kpMz9i FF2f+BTJtVXSgETAOle8Zubc11o534cuI6aNM5ljonIeya8zbuMtHh+dUIdG1idJr8Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794063455; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=ONjToDKfkP38/LFDjdQWLeil8Lm33Wp0GIfIMyCgUg4=; b=S+rawblyj/FjqQFA5MVDYdjCEa43Fu8d2fuTFZ3X3GlqL6q0KkgrYv9+rtxm/qvmOIzr mQMn7hXQwJKqU2S8Vj6DPuv1Wti2IFOZTIY9bVnbA0f7LtQvfHb7HmegWcp2fnpTb7Nv9 FFJYYIzSzMq3EsWNmS5nzIeA9HT708+xp8xN0kLrvYaonVTTKM35Nh7vkjraykZlLUpx+ vMCBIEmIcrzyYb2b8GhstkjV+gQrO92e/J5IJBvXsRMKCUfFljdJRsRuCDcxoW7rzIU8p VeCgojZn4GwkEv5dcHxA8RXsX+CJVSEVJxaglACxAZjkMFUnOJPgyN/Jf3Kyu5A9FYA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=EnEZyHus; 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 9367660A5BC9; Sat, 7 Nov 2026 14:57:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=EnEZyHus Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF9121F008A1; Sat, 7 Nov 2026 14:57:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794063455; bh=ONjToDKfkP38/LFDjdQWLeil8Lm33Wp0GIfIMyCgUg4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EnEZyHus9YsIMTp+GDTJBGhb15JJB2M8T58FoUvUoZlUkY1jjUyrssRZD0eJuOlFD jSwnBbJIJzB9mOpduzuBTkvZPs2UJ0Ngmi0BNTa+6NBI+J9q7Quw02q5SiQGv7UB+3 4IpeqQvY4/BQld65iF6oBcDTvhLJ0uWAgU+0FfMw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Song Li , Fan Wu , Miklos Szeredi , Sasha Levin Subject: [PATCH 6.18 612/869] virtio_fs: read the vring size under virtio_fs_mutex in ->get_tree Date: Sat, 7 Nov 2026 08:54:54 -0500 Message-ID: <20261107134913.821311900@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134852.069646174@linuxfoundation.org> References: <20261107134852.069646174@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Fan Wu [ Upstream commit e7ccc777a040343b80f95f4cc5c12ce1df3187f4 ] 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 Signed-off-by: Sasha Levin --- 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 2b3daa93e299a..e475f7f9e83d4 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -454,26 +454,23 @@ 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) @@ -1675,13 +1672,17 @@ static int virtio_fs_get_tree(struct fs_context *fsc) * in fc->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