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Thu, 2 Sep 2021 17:09:08 +0000 From: Michael Kelley To: vkuznets , "linux-hyperv@vger.kernel.org" CC: Andres Beltran , "Andrea Parri (Microsoft)" , Dexuan Cui , Wei Liu , Stephen Hemminger , Haiyang Zhang , KY Srinivasan , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] Drivers: hv: vmbus: Fix kernel crash upon unbinding a device from uio_hv_generic driver Thread-Topic: [PATCH] Drivers: hv: vmbus: Fix kernel crash upon unbinding a device from uio_hv_generic driver Thread-Index: AQHXnnYBTI4PTSpBKkqF5K5fFbYk7KuQ/Vyg Date: Thu, 2 Sep 2021 17:09:08 +0000 Message-ID: References: <20210831143916.144983-1-vkuznets@redhat.com> In-Reply-To: <20210831143916.144983-1-vkuznets@redhat.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_ActionId=35c05d14-4c0e-4aa8-9af9-3f7db01f8edc;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_ContentBits=0;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Enabled=true;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Method=Standard;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Name=Internal;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_SetDate=2021-09-02T17:08:25Z;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_SiteId=72f988bf-86f1-41af-91ab-2d7cd011db47; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: MWHPR21MB1593.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 493de44d-2ebe-473f-a463-08d96e3460b3 X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Sep 2021 17:09:08.7457 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: uYG8rCUpfcO2II3fDY+0pK1SxvfUJjG+Dt3QLnYWv7nSdizs51YuaKSmLCJjmPf2B/sit1uMk0Z0EGM/eH5uXgk8HLq96oGQVHROW+2244o= X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR21MB2041 Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org From: Vitaly Kuznetsov Sent: Tuesday, August 31, 2021= 7:39 AM >=20 > The following crash happens when a never-used device is unbound from > uio_hv_generic driver: >=20 > kernel BUG at mm/slub.c:321! > invalid opcode: 0000 [#1] SMP PTI > CPU: 0 PID: 4001 Comm: bash Kdump: loaded Tainted: G X ---= ------ --- 5.14.0-0.rc2.23.el9.x86_64 #1 > Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BI= OS 090008 12/07/2018 > RIP: 0010:__slab_free+0x1d5/0x3d0 > ... > Call Trace: > ? pick_next_task_fair+0x18e/0x3b0 > ? __cond_resched+0x16/0x40 > ? vunmap_pmd_range.isra.0+0x154/0x1c0 > ? __vunmap+0x22d/0x290 > ? hv_ringbuffer_cleanup+0x36/0x40 [hv_vmbus] > kfree+0x331/0x380 > ? hv_uio_remove+0x43/0x60 [uio_hv_generic] > hv_ringbuffer_cleanup+0x36/0x40 [hv_vmbus] > vmbus_free_ring+0x21/0x60 [hv_vmbus] > hv_uio_remove+0x4f/0x60 [uio_hv_generic] > vmbus_remove+0x23/0x30 [hv_vmbus] > __device_release_driver+0x17a/0x230 > device_driver_detach+0x3c/0xa0 > unbind_store+0x113/0x130 > ... >=20 > The problem appears to be that we free 'ring_info->pkt_buffer' twice: > first, when the device is unbound from in-kernel driver (netvsc in this > case) and second from hv_uio_remove(). Normally, ring buffer is supposed > to be re-initialized from hv_uio_open() but this happens when UIO device > is being opened and this is not guaranteed to happen. >=20 > Generally, it is OK to call hv_ringbuffer_cleanup() twice for the same > channel (which is being handed over between in-kernel drivers and UIO) ev= en > if we didn't call hv_ringbuffer_init() in between. We, however, need to > avoid kfree() call for an already freed pointer. >=20 > Fixes: adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V ou= t of the ring buffer") > Signed-off-by: Vitaly Kuznetsov > --- > drivers/hv/ring_buffer.c | 1 + > 1 file changed, 1 insertion(+) >=20 > diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c > index 2aee356840a2..314015d9e912 100644 > --- a/drivers/hv/ring_buffer.c > +++ b/drivers/hv/ring_buffer.c > @@ -245,6 +245,7 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info= *ring_info) > mutex_unlock(&ring_info->ring_buffer_mutex); >=20 > kfree(ring_info->pkt_buffer); > + ring_info->pkt_buffer =3D NULL; > ring_info->pkt_buffer_size =3D 0; > } >=20 > -- > 2.31.1 Reviewed-by: Michael Kelley