KASAN: slab-out-of-bounds Read in au0828_rc_unregister (2)

KASAN: slab-out-of-bounds Read in au0828_rc_unregister (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    43151d6c usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=162ca944a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=95aff7278e7ff25e
dashboard link: https://syzkaller.appspot.com/bug?extid=357d86bcb4cca1a2f572
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+357d86bcb4cca1a2f572@syzkaller.appspotmail.com

au0828: recv_control_msg() Failed receiving control message, error -71.
au0828: recv_control_msg() Failed receiving control message, error -71.
au0828: recv_control_msg() Failed receiving control message, error -71.
au8522_writereg: writereg error (reg == 0x106, val == 0x0001, ret == -5)
usb 4-1: selecting invalid altsetting 5
au0828: Failure setting usb interface0 to as5
au0828: au0828_usb_probe() au0828_analog_register failed to register on V4L2
==================================================================
BUG: KASAN: slab-out-of-bounds in au0828_rc_unregister+0x9a/0xb0  
drivers/media/usb/au0828/au0828-input.c:353
Read of size 8 at addr ffff8881cb76f308 by task kworker/1:5/5626

CPU: 1 PID: 5626 Comm: kworker/1:5 Not tainted 5.1.0-rc3+ #8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0xca/0x13e lib/dump_stack.c:113
  print_address_description+0x67/0x231 mm/kasan/report.c:187
  kasan_report.cold+0x1a/0x35 mm/kasan/report.c:317
  au0828_rc_unregister+0x9a/0xb0 drivers/media/usb/au0828/au0828-input.c:353
  au0828_usb_disconnect+0x6a/0x130 drivers/media/usb/au0828/au0828-core.c:189
  au0828_usb_probe.cold+0x111/0x16e  
drivers/media/usb/au0828/au0828-core.c:661
  usb_probe_interface+0x30d/0x7b0 drivers/usb/core/driver.c:361
  really_probe+0x296/0x680 drivers/base/dd.c:509
  driver_probe_device+0xf9/0x200 drivers/base/dd.c:671
  __device_attach_driver+0x1c4/0x230 drivers/base/dd.c:778
  bus_for_each_drv+0x15e/0x1e0 drivers/base/bus.c:454
  __device_attach+0x21e/0x360 drivers/base/dd.c:844
  bus_probe_device+0x1ec/0x2a0 drivers/base/bus.c:514
  device_add+0xaf4/0x1700 drivers/base/core.c:2106
  usb_set_configuration+0xdf2/0x1670 drivers/usb/core/message.c:2023
  generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
  usb_probe_device+0xa8/0x110 drivers/usb/core/driver.c:266
  really_probe+0x296/0x680 drivers/base/dd.c:509
  driver_probe_device+0xf9/0x200 drivers/base/dd.c:671
  __device_attach_driver+0x1c4/0x230 drivers/base/dd.c:778
  bus_for_each_drv+0x15e/0x1e0 drivers/base/bus.c:454
  __device_attach+0x21e/0x360 drivers/base/dd.c:844
  bus_probe_device+0x1ec/0x2a0 drivers/base/bus.c:514
  device_add+0xaf4/0x1700 drivers/base/core.c:2106
  usb_new_device.cold+0x8b8/0x1030 drivers/usb/core/hub.c:2534
  hub_port_connect drivers/usb/core/hub.c:5089 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
  port_event drivers/usb/core/hub.c:5350 [inline]
  hub_event+0x1ac9/0x35a0 drivers/usb/core/hub.c:5432
  process_one_work+0x90a/0x1580 kernel/workqueue.c:2269
  worker_thread+0x96/0xe20 kernel/workqueue.c:2415
  kthread+0x30e/0x420 kernel/kthread.c:253
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

The buggy address belongs to the page:
page:ffffea00072ddb00 count:1 mapcount:0 mapping:0000000000000000 index:0x0  
compound_mapcount: 0
flags: 0x200000000010000(head)
raw: 0200000000010000 dead000000000100 dead000000000200 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881cb76f200: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
  ffff8881cb76f280: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
> ffff8881cb76f300: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
                       ^
  ffff8881cb76f380: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
  ffff8881cb76f400: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
==================================================================


---
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[PATCH] media: au0828: fix null dereference in error path

[Sean Young]

au0828_usb_disconnect() gets the au0828_dev struct via usb_get_intfdata,
so it needs to set up for the error paths.

Reported-by: syzbot+357d86bcb4cca1a2f572@syzkaller.appspotmail.com
Signed-off-by: Sean Young <sean@mess.org>
---
 drivers/media/usb/au0828/au0828-core.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/media/usb/au0828/au0828-core.c b/drivers/media/usb/au0828/au0828-core.c
index 925a80437822..e306d5d5bebb 100644
--- a/drivers/media/usb/au0828/au0828-core.c
+++ b/drivers/media/usb/au0828/au0828-core.c
@@ -729,6 +729,12 @@ static int au0828_usb_probe(struct usb_interface *interface,
 	/* Setup */
 	au0828_card_setup(dev);
 
+	/*
+	 * Store the pointer to the au0828_dev so it can be accessed in
+	 * au0828_usb_disconnect
+	 */
+	usb_set_intfdata(interface, dev);
+
 	/* Analog TV */
 	retval = au0828_analog_register(dev, interface);
 	if (retval) {
@@ -747,12 +753,6 @@ static int au0828_usb_probe(struct usb_interface *interface,
 	/* Remote controller */
 	au0828_rc_register(dev);
 
-	/*
-	 * Store the pointer to the au0828_dev so it can be accessed in
-	 * au0828_usb_disconnect
-	 */
-	usb_set_intfdata(interface, dev);
-
 	pr_info("Registered device AU0828 [%s]\n",
 		dev->board.name == NULL ? "Unset" : dev->board.name);
 
-- 
2.20.1