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=1794422380; b=JLKXIvyznorvyGN9Z2V6qlDSgTMDsOf7qFHs0XK9fIv//3wjN48DMAtv3MHVXLa6+Tcr QOoy39DAqxK14LenUwYO2oB9rPdoyNIyUip6OXqAzPbFKr0uWH3/cpWMqpOia6x4zszbz 9SLpZ61PPip3v/xWjoC6Y3jWdQTVUBRbBgY6T6cUOTiNJOF2heeJZLMfcgqUEhVyQ84l/ zzr40SuZXa7soh9MXoUZlzEj2llk6PBMqR7ohnV9fOi6BfRCHxRYRf+13abyaIZZzGW3x vdfnWpY404lf0XLTzIKuatwVJSulyqyWS99cL7KSi7DMsqlP5sH4SNm5gBWFLOphhyA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794422380; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=+z3GRDRtq55awDwm+JWYhbM+Y2Izrq3GJ/31r0mSVMY=; b=SFlmmqzaFBwkXb2rDv+JQ/XZGRhG/3omAV6buZyGSX+iNw5M5Q8oFBGHZS4YdJGsaTtT mdmkR+e+QBk6HWDrvckbVwwMCnZnXQ4RZoPYz91la16YdjeNvhKCDrq+ycX03vz4IZpS4 LdoGmGpU4SuGaGC09anJgJYHSAGuBPRNKi4R96T36PGPzGoEBJJU4VegxAyQl1kt9psSj BSpQbNHWnR0Nonokf40KlLFvdboDF5wV5MFEfcjO6YScPIvz2dxL4UcZY9+fUMJGITVmu 4qcxeJBpVgKrPakJhBDdXFU4R0vPZMR4o0RsACH4qfjpaPPJND71dQSWLKUtEYpZfXg== 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=Opt7hnu0; 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 0BA2F606A321 for ; Wed, 11 Nov 2026 18:39:39 +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=Opt7hnu0 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1BFDD1F00A06; Wed, 11 Nov 2026 18:39:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794422379; bh=+z3GRDRtq55awDwm+JWYhbM+Y2Izrq3GJ/31r0mSVMY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Opt7hnu0kS7bplynYdQ7arbrcrQ9yU4n2Nuf2uXwSd20HJi2Y9o6+/vHx5EQXteqn tbsBAgZ7mD9F3eXYYfAmmeCs4tfI9/HatuMpOuYcjFKtiMnCeFOjR3LznHnyczV2Mt pnZMnht2PNIvgtLYhSYdfhO/WWUrytBkO6wyZBXx+yBsNAa3IZU5c2VqehIjZ7/i0r WYJnbIHkN4VHzYvqBH28j7KfNXg83uh6WlI5RNO9OFCyXechv7SwDRIhmKe7MdBwRr C2iWJ4lwESt7PAVfGPXRuAE/LldtTYtVywcOjW/nRkJvFyfhs/OuPGDHNNpmz9qKL+ qd/u3xTFWRuMw== From: Sasha Levin To: stable@vger.kernel.org Cc: Fan Wu , Song Li , Miklos Szeredi , Sasha Levin Subject: [PATCH 5.10.y] virtio_fs: read the vring size under virtio_fs_mutex in ->get_tree Date: Wed, 11 Nov 2026 13:39:37 -0500 Message-ID: <20261111183913.3875898-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107062439-failed-5.10-e7ccc777a040@kernel.org> References: <20261107062439-failed-5.10-e7ccc777a040@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: 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 [ sashal: adjusted context for kref_get(&fs->refcount) instead of kobject_get(&fs->kobj) ] 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 d405cdf36247c..e3424fc12b80b 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -257,26 +257,23 @@ static int virtio_fs_add_instance(struct virtio_fs *fs) return 0; } -/* 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) { kref_get(&fs->refcount); - 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) @@ -1454,13 +1451,17 @@ 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