From:   Parav Pandit <parav@nvidia.com>
To:     "Longpeng(Mike)" <longpeng2@huawei.com>,
        "mst@redhat.com" <mst@redhat.com>,
        "jasowang@redhat.com" <jasowang@redhat.com>
CC:     "sgarzare@redhat.com" <sgarzare@redhat.com>,
        Max Gurtovoy <mgurtovoy@nvidia.com>,
        "virtualization@lists.linux-foundation.org" 
        <virtualization@lists.linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "arei.gonglei@huawei.com" <arei.gonglei@huawei.com>
Subject: RE: [PATCH] vdpa_sim: avoid putting an uninitialized iova_domain
Thread-Topic: [PATCH] vdpa_sim: avoid putting an uninitialized iova_domain
Thread-Index: AQHX35ueaWYQw4IqXUGs9TH2rQN8bawQcIOA
Date:   Tue, 23 Nov 2021 03:12:31 +0000
Message-ID: <PH0PR12MB54811F4CC671312DFB2FACCDDC609@PH0PR12MB5481.namprd12.prod.outlook.com>
References: <20211122122221.56-1-longpeng2@huawei.com>
In-Reply-To: <20211122122221.56-1-longpeng2@huawei.com>
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> From: Longpeng(Mike) <longpeng2@huawei.com>
> Sent: Monday, November 22, 2021 5:52 PM
>=20
> From: Longpeng <longpeng2@huawei.com>
>=20
> The system will crash if we put an uninitialized iova_domain, this could
> happen when an error occurs before initializing the iova_domain in
> vdpasim_create().
>=20
> BUG: kernel NULL pointer dereference, address: 0000000000000000 ...
> RIP: 0010:__cpuhp_state_remove_instance+0x96/0x1c0
> ...
> Call Trace:
>  <TASK>
>  put_iova_domain+0x29/0x220
>  vdpasim_free+0xd1/0x120 [vdpa_sim]
>  vdpa_release_dev+0x21/0x40 [vdpa]
>  device_release+0x33/0x90
>  kobject_release+0x63/0x160
>  vdpasim_create+0x127/0x2a0 [vdpa_sim]
>  vdpasim_net_dev_add+0x7d/0xfe [vdpa_sim_net]
>  vdpa_nl_cmd_dev_add_set_doit+0xe1/0x1a0 [vdpa]
>  genl_family_rcv_msg_doit+0x112/0x140
>  genl_rcv_msg+0xdf/0x1d0
>  ...
>=20
> So we must make sure the iova_domain is already initialized before put it=
.
>=20
> In addition, we may get the following warning in this case:
> WARNING: ... drivers/iommu/iova.c:344 iova_cache_put+0x58/0x70
>=20
> So we must make sure the iova_cache_put() is invoked only if the
> iova_cache_get() is already invoked. Let's fix it together.
>=20
> Signed-off-by: Longpeng <longpeng2@huawei.com>

Can you please add the fixes tag here so that older kernels can take this f=
ix?