linux-kernel - Re: [PATCH] vfio: Fix NULL pointer dereference caused by uninitialized group->iommufd

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Date:   Wed, 22 Feb 2023 10:59:42 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Yan Zhao <yan.y.zhao@...el.com>
Cc:     jgg@...dia.com, kevin.tian@...el.com, yi.l.liu@...el.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vfio: Fix NULL pointer dereference caused by
 uninitialized group->iommufd

On Wed, 22 Feb 2023 15:49:38 +0800
Yan Zhao <yan.y.zhao@...el.com> wrote:

> group->iommufd is not initialized for the iommufd_ctx_put()
> 
> [20018.331541] BUG: kernel NULL pointer dereference, address: 0000000000000000
> [20018.377508] RIP: 0010:iommufd_ctx_put+0x5/0x10 [iommufd]
> ...
> [20018.476483] Call Trace:
> [20018.479214]  <TASK>
> [20018.481555]  vfio_group_fops_unl_ioctl+0x506/0x690 [vfio]
> [20018.487586]  __x64_sys_ioctl+0x6a/0xb0
> [20018.491773]  ? trace_hardirqs_on+0xc5/0xe0
> [20018.496347]  do_syscall_64+0x67/0x90
> [20018.500340]  entry_SYSCALL_64_after_hwframe+0x4b/0xb5
> 
> Fixes: 9eefba8002c2 ("vfio: Move vfio group specific code into group.c")
> Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
> ---
>  drivers/vfio/group.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
> index 57ebe5e1a7e6..8649f85f3be4 100644
> --- a/drivers/vfio/group.c
> +++ b/drivers/vfio/group.c
> @@ -137,7 +137,7 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group,
>  
>  		ret = iommufd_vfio_compat_ioas_id(iommufd, &ioas_id);
>  		if (ret) {
> -			iommufd_ctx_put(group->iommufd);
> +			iommufd_ctx_put(iommufd);
>  			goto out_unlock;
>  		}
>  

Applied to vfio next branch for v6.3 and added a stable cc.  Thanks,

Alex