From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A192D4D37B0; Thu, 1 Oct 2026 09:32:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790847122; cv=none; b=qVc9r4MzVB0mnl0iMcvRj/90z7c180aBDzRW++/dt1UYsH+RmcgUqXiLGKttdCpPZUnq9Nos7tqXJme0La2Ht3QmjsI7+p7gGmZRIDw4NoNgbumJ6wOKvWw6B+f5rLUm4SW4qnrUsLZB99P7kf1Gx6nTIH3PmRqqN9t3rncdrhU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790847122; c=relaxed/simple; bh=2L3GHBgKnxNfEISMFOnCHgNLDM0Kl4d0dR1aAm/XekY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=sY6DwQ5JklIeRQVGvg8rqM2bFMXK+zYGoGqJzApwXOaPMc9Aeg5k8gUhQLyq4w2nt5Wv3R+/wjL0+jHF0Eua7fv6d8WNYYT8hYyBElYI7Ge7oj0L0B5ssrE54clbk3iHjNZymqMpMrlJuDnnac1Ju2bISCzMYvdfPX1rJOHOBvU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Eu0Nc7VI; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Eu0Nc7VI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AEC3A1F000FF; Thu, 1 Oct 2026 09:31:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790847120; bh=Q8nH4a9zyuqymi5cvucxrHlyiGUE1EZm5MBlxkRW3Lc=; h=From:To:Cc:Subject:Date; b=Eu0Nc7VIX1Bk59LO+H+6uZvTd34u0rhQzJC/lxF0nGzQLXV55JlOPs5wz3Rl0wrNc 6fqH4KGTfGLgSr9vfjDOusR16vgpiHmKduaK+HEOXitkAG/LSieMV34eRz1b9jyyC2 6DJZR7ElCCozC8G8SlwprGsCd20GWf9tw7jE6ofAH+v1/cj7ZgdomLmBDMKIYr4cWn OJBm00Ii7bqSQFEZrXyHoK1kQV27FBskKFy60OrKHoqNN425QeURN3nj3lqUXt/U7v yDOYJmWaHrez9An5jeFPUbHTNiVxiAb8K/hXzXFQKJTT+SeW4yx11AAdeBVdzF9sIM USyVSkm3dAUlg== From: "Aneesh Kumar K.V (Arm)" To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Aneesh Kumar K.V (Arm)" , Alex Williamson Subject: [PATCH] vfio: cdev: Reject duplicate bind before updating KVM file Date: Thu, 1 Oct 2026 15:01:52 +0530 Message-ID: <20261001093152.1698474-1-aneesh.kumar@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The cdev path only supports one bound/open device fd, but VFIO_DEVICE_BIND_IOMMUFD only checked the per-file access_granted flag before capturing the KVM file reference. A second fd for the same device could therefore replace device->kvm, fail later in vfio_df_open() because open_count is already nonzero, and then clear the active KVM association during error cleanup. Reject the bind while holding dev_set->lock if the device is already open, matching the existing cdev single-open rule before touching the device-wide KVM state. Cc: Alex Williamson Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Aneesh Kumar K.V (Arm) --- drivers/vfio/device_cdev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c index 1d9515c967b0..ab46563604ac 100644 --- a/drivers/vfio/device_cdev.c +++ b/drivers/vfio/device_cdev.c @@ -124,8 +124,8 @@ long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df, return ret; mutex_lock(&device->dev_set->lock); - /* one device cannot be bound twice */ - if (df->access_granted) { + /* The cdev path only supports one bound/open device fd. */ + if (df->access_granted || device->open_count) { ret = -EINVAL; goto out_unlock; } -- 2.43.0