linux-kernel - Re: [PATCH 1/2] vfio: Fix unbalanced vfio_df

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250526235222.GI61950@nvidia.com>
Date: Mon, 26 May 2025 20:52:22 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Jacob Pan <jacob.pan@...ux.microsoft.com>
Cc: linux-kernel@...r.kernel.org,
	"iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
	Alex Williamson <alex.williamson@...hat.com>,
	"Liu, Yi L" <yi.l.liu@...el.com>, Zhang Yu <zhangyu1@...rosoft.com>,
	Easwar Hariharan <eahariha@...ux.microsoft.com>
Subject: Re: [PATCH 1/2] vfio: Fix unbalanced vfio_df_close call in no-iommu
 mode

On Fri, May 16, 2025 at 09:45:21AM -0700, Jacob Pan wrote:
> For no-iommu enabled devices working under IOMMUFD VFIO compat mode, the
> group open path does not call vfio_df_open() and the open_count is 0. So
> calling vfio_df_close() in the group close path will trigger warning in
> vfio_assert_device_open(device);
> 
> E.g. The following warning can be seen by running VFIO test.
> https://github.com/awilliam/tests/blob/master/vfio-noiommu-pci-device-open.c
> CONFIG_VFIO_CONTAINER = n
> [   29.094781] vfio-pci 0000:02:01.0: vfio-noiommu device opened by user (vfio-noiommu-pc:164)
> Failed to get device info
> [   29.096540] ------------[ cut here ]------------
> [   29.096616] WARNING: CPU: 1 PID: 164 at drivers/vfio/vfio_main.c:487 vfio_df_close+0xac/0xb4
> 
> This patch adds checks for no-iommu mode and open_count to skip calling vfio_df_close.
> 
> Signed-off-by: Jacob Pan <jacob.pan@...ux.microsoft.com>
> ---
>  drivers/vfio/group.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason