From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6CBD92F5E; Tue, 12 Aug 2025 18:00:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755021645; cv=none; b=SoAF05feZDIYdso2cbQ95ggqU5VKe7w3sPCBLi1A5oMt748h1E0gmg3acHh/JpiWW9dfi/JclTXP/FOqjQUkA+9JU+tvQ9NWAPvyVfdv2KaKvSC+4i/MqjENHlMXyCh95VqoSHJgUVRtozovU+/HRmDBbn7/t+tp28QvQur+TMw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755021645; c=relaxed/simple; bh=eSdGM69uLh9t/NqLFBy85KizdA34I8UR+GmwWtijDmo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fUz9Y360LaIn6uvYqBC5tYPUVadLgNNtFoB2FxGnp0P1x0S+Io8adsmc/SynbMJ0pcM7w42jCIfVQSXPm5JzsoF2XCWFdvfwiKiERi1edG6TvmotO/53IHR1Bq7bKAmwySmD2a5GarDHaHnym8Lc+hs4o+8aLr+cA9s8pyi9UPw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kO3eg/Ik; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="kO3eg/Ik" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF6EBC4CEF0; Tue, 12 Aug 2025 18:00:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755021645; bh=eSdGM69uLh9t/NqLFBy85KizdA34I8UR+GmwWtijDmo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kO3eg/Ikyb4oFM4v+A/qOpBGdaMfDh/ne0pzIeD1sCOeN7UOCNo/uA7E2e3vGYypH ByN/GzQM2Jh/4yxlVUOJrfp+s5wdbwhzIF/YMXka2zznQVXtAcxqr6NTjWcCE977xg gEUfrBRIFEKo6Gc2nYF1czK4MAc7iwG93Dsst1qw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jason Gunthorpe , Yi Liu , Jacob Pan , Alex Williamson , Sasha Levin Subject: [PATCH 6.6 182/262] vfio: Prevent open_count decrement to negative Date: Tue, 12 Aug 2025 19:29:30 +0200 Message-ID: <20250812173000.874359364@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250812172952.959106058@linuxfoundation.org> References: <20250812172952.959106058@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jacob Pan [ Upstream commit 982ddd59ed97dc7e63efd97ed50273ffb817bd41 ] When vfio_df_close() is called with open_count=0, it triggers a warning in vfio_assert_device_open() but still decrements open_count to -1. This allows a subsequent open to incorrectly pass the open_count == 0 check, leading to unintended behavior, such as setting df->access_granted = true. For example, running an IOMMUFD compat no-IOMMU device with VFIO tests (https://github.com/awilliam/tests/blob/master/vfio-noiommu-pci-device-open.c) results in a warning and a failed VFIO_GROUP_GET_DEVICE_FD ioctl on the first run, but the second run succeeds incorrectly. Add checks to avoid decrementing open_count below zero. Fixes: 05f37e1c03b6 ("vfio: Pass struct vfio_device_file * to vfio_device_open/close()") Reviewed-by: Jason Gunthorpe Reviewed-by: Yi Liu Signed-off-by: Jacob Pan Link: https://lore.kernel.org/r/20250618234618.1910456-2-jacob.pan@linux.microsoft.com Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin --- drivers/vfio/vfio_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index 40732e8ed4c6..edb631e5e7ec 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -537,7 +537,8 @@ void vfio_df_close(struct vfio_device_file *df) lockdep_assert_held(&device->dev_set->lock); - vfio_assert_device_open(device); + if (!vfio_assert_device_open(device)) + return; if (device->open_count == 1) vfio_df_device_last_close(df); device->open_count--; -- 2.39.5