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

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Message-ID: <a4ad3fd15d41feda354ed50feaaccbe73e945d16.camel@gmail.com>
Date:   Wed, 22 Feb 2023 10:18:28 +0100
From:   Miko Larsson <mikoxyzzz@...il.com>
To:     Yan Zhao <yan.y.zhao@...el.com>, alex.williamson@...hat.com,
        jgg@...dia.com, kevin.tian@...el.com
Cc:     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, 2023-02-22 at 15:49 +0800, Yan Zhao 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;
>                 }
>  

Might want to Cc this to the stable mailing list.
-- 
~miko