From: "Zhu, Lingshan" <lingshan.zhu@intel.com>
To: Stefano Garzarella <sgarzare@redhat.com>,
virtualization@lists.linux-foundation.org
Cc: Jason Wang <jasowang@redhat.com>,
netdev@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH 1/2] vhost-vdpa: fix use-after-free of v->config_ctx
Date: Fri, 12 Mar 2021 09:37:14 +0800 [thread overview]
Message-ID: <82e63dc0-7589-98f7-0ea5-dd86ce64949d@intel.com> (raw)
In-Reply-To: <20210311135257.109460-2-sgarzare@redhat.com>
On 3/11/2021 9:52 PM, Stefano Garzarella wrote:
> When the 'v->config_ctx' eventfd_ctx reference is released we didn't
> set it to NULL. So if the same character device (e.g. /dev/vhost-vdpa-0)
> is re-opened, the 'v->config_ctx' is invalid and calling again
> vhost_vdpa_config_put() causes use-after-free issues like the
> following refcount_t underflow:
>
> refcount_t: underflow; use-after-free.
> WARNING: CPU: 2 PID: 872 at lib/refcount.c:28 refcount_warn_saturate+0xae/0xf0
> RIP: 0010:refcount_warn_saturate+0xae/0xf0
> Call Trace:
> eventfd_ctx_put+0x5b/0x70
> vhost_vdpa_release+0xcd/0x150 [vhost_vdpa]
> __fput+0x8e/0x240
> ____fput+0xe/0x10
> task_work_run+0x66/0xa0
> exit_to_user_mode_prepare+0x118/0x120
> syscall_exit_to_user_mode+0x21/0x50
> ? __x64_sys_close+0x12/0x40
> do_syscall_64+0x45/0x50
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Fixes: 776f395004d8 ("vhost_vdpa: Support config interrupt in vdpa")
> Cc: lingshan.zhu@intel.com
> Cc: stable@vger.kernel.org
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
> drivers/vhost/vdpa.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index ef688c8c0e0e..00796e4ecfdf 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -308,8 +308,10 @@ static long vhost_vdpa_get_vring_num(struct vhost_vdpa *v, u16 __user *argp)
>
> static void vhost_vdpa_config_put(struct vhost_vdpa *v)
> {
> - if (v->config_ctx)
> + if (v->config_ctx) {
> eventfd_ctx_put(v->config_ctx);
> + v->config_ctx = NULL;
> + }
> }
>
> static long vhost_vdpa_set_config_call(struct vhost_vdpa *v, u32 __user *argp)
Thanks Stefano!
Reviewed-by: Zhu Lingshan <lingshan.zhu@intel.com>
next prev parent reply other threads:[~2021-03-12 1:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-11 13:52 [PATCH 0/2] vhost-vdpa: fix issues around v->config_ctx handling Stefano Garzarella
2021-03-11 13:52 ` [PATCH 1/2] vhost-vdpa: fix use-after-free of v->config_ctx Stefano Garzarella
2021-03-12 1:37 ` Zhu, Lingshan [this message]
2021-03-12 6:33 ` Jason Wang
2021-03-11 13:52 ` [PATCH 2/2] vhost-vdpa: set v->config_ctx to NULL if eventfd_ctx_fdget() fails Stefano Garzarella
2021-03-12 6:34 ` Jason Wang
2021-03-11 16:42 ` [PATCH 0/2] vhost-vdpa: fix issues around v->config_ctx handling Michael S. Tsirkin
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