[PATCH 3.16 15/72] media: tm6000: double free if usb disconnect while streaming

Ben Hutchings
2019-12-08T13:58:29Z

From: Sean Young <sean@mess.org>

commit 699bf94114151aae4dceb2d9dbf1a6312839dcae upstream.

The usb_bulk_urb will kfree'd on disconnect, so ensure the pointer is set
to NULL after each free.

stop stream
urb killing
urb buffer free
tm6000: got start feed request tm6000_start_feed
tm6000: got start stream request tm6000_start_stream
tm6000: pipe reset
tm6000: got start feed request tm6000_start_feed
tm6000: got start feed request tm6000_start_feed
tm6000: got start feed request tm6000_start_feed
tm6000: got start feed request tm6000_start_feed
tm6000: IR URB failure: status: -71, length 0
xhci_hcd 0000:00:14.0: ERROR unknown event type 37
xhci_hcd 0000:00:14.0: ERROR unknown event type 37
tm6000: error tm6000_urb_received
usb 1-2: USB disconnect, device number 5
tm6000: disconnecting tm6000 #0
==================================================================
BUG: KASAN: use-after-free in dvb_fini+0x75/0x140 [tm6000_dvb]
Read of size 8 at addr ffff888241044060 by task kworker/2:0/22

CPU: 2 PID: 22 Comm: kworker/2:0 Tainted: G W 5.3.0-rc4+ #1
Hardware name: LENOVO 20KHCTO1WW/20KHCTO1WW, BIOS N23ET65W (1.40 ) 07/02/2019
Workqueue: usb_hub_wq hub_event
Call Trace:
dump_stack+0x9a/0xf0
print_address_description.cold+0xae/0x34f
__kasan_report.cold+0x75/0x93
? tm6000_fillbuf+0x390/0x3c0 [tm6000_alsa]
? dvb_fini+0x75/0x140 [tm6000_dvb]
kasan_report+0xe/0x12
dvb_fini+0x75/0x140 [tm6000_dvb]
tm6000_close_extension+0x51/0x80 [tm6000]
tm6000_usb_disconnect.cold+0xd4/0x105 [tm6000]
usb_unbind_interface+0xe4/0x390
device_release_driver_internal+0x121/0x250
bus_remove_device+0x197/0x260
device_del+0x268/0x550
? __device_links_no_driver+0xd0/0xd0
? usb_remove_ep_devs+0x30/0x3b
usb_disable_device+0x122/0x400
usb_disconnect+0x153/0x430
hub_event+0x800/0x1e40
? trace_hardirqs_on_thunk+0x1a/0x20
? hub_port_debounce+0x1f0/0x1f0
? retint_kernel+0x10/0x10
? lock_is_held_type+0xf1/0x130
? hub_port_debounce+0x1f0/0x1f0
? process_one_work+0x4ae/0xa00
process_one_work+0x4ba/0xa00
? pwq_dec_nr_in_flight+0x160/0x160
? do_raw_spin_lock+0x10a/0x1d0
worker_thread+0x7a/0x5c0
? process_one_work+0xa00/0xa00
kthread+0x1d5/0x200
? kthread_create_worker_on_cpu+0xd0/0xd0
ret_from_fork+0x3a/0x50

Allocated by task 2682:
save_stack+0x1b/0x80
__kasan_kmalloc.constprop.0+0xc2/0xd0
usb_alloc_urb+0x28/0x60
tm6000_start_feed+0x10a/0x300 [tm6000_dvb]
dmx_ts_feed_start_filtering+0x86/0x120 [dvb_core]
dvb_dmxdev_start_feed+0x121/0x180 [dvb_core]
dvb_dmxdev_filter_start+0xcb/0x540 [dvb_core]
dvb_demux_do_ioctl+0x7ed/0x890 [dvb_core]
dvb_usercopy+0x97/0x1f0 [dvb_core]
dvb_demux_ioctl+0x11/0x20 [dvb_core]
do_vfs_ioctl+0x5d8/0x9d0
ksys_ioctl+0x5e/0x90
__x64_sys_ioctl+0x3d/0x50
do_syscall_64+0x74/0xe0
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 22:
save_stack+0x1b/0x80
__kasan_slab_free+0x12c/0x170
kfree+0xfd/0x3a0
xhci_giveback_urb_in_irq+0xfe/0x230
xhci_td_cleanup+0x276/0x340
xhci_irq+0x1129/0x3720
__handle_irq_event_percpu+0x6e/0x420
handle_irq_event_percpu+0x6f/0x100
handle_irq_event+0x55/0x84
handle_edge_irq+0x108/0x3b0
handle_irq+0x2e/0x40
do_IRQ+0x83/0x1a0

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/media/usb/tm6000/tm6000-dvb.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/media/usb/tm6000/tm6000-dvb.c
+++ b/drivers/media/usb/tm6000/tm6000-dvb.c
@@ -111,6 +111,7 @@ static void tm6000_urb_received(struct u
printk(KERN_ERR "tm6000: error %s\n", __func__);
kfree(urb->transfer_buffer);
usb_free_urb(urb);
+ dev->dvb->bulk_urb = NULL;
}
}
}
@@ -143,6 +144,7 @@ static int tm6000_start_stream(struct tm
dvb->bulk_urb->transfer_buffer = kzalloc(size, GFP_KERNEL);
if (dvb->bulk_urb->transfer_buffer == NULL) {
usb_free_urb(dvb->bulk_urb);
+ dvb->bulk_urb = NULL;
printk(KERN_ERR "tm6000: couldn't allocate transfer buffer!\n");
return -ENOMEM;
}
@@ -170,6 +172,7 @@ static int tm6000_start_stream(struct tm

kfree(dvb->bulk_urb->transfer_buffer);
usb_free_urb(dvb->bulk_urb);
+ dvb->bulk_urb = NULL;
return ret;
}