A use-after-free bug occures when unbinding the device while it streams.
The 'struct vimc_ent_device' allocated for the 'Sensor A' is freed
when calling the sensor's 'rm' callback but the freed pointer is
later accessed in the function 'vimc_streamer_pipeline_terminate'.
To fix this bug, move the release callback of the vimc entities
and vimc_device to the release callback of v4l2_device.
The .rm callback of vimc_ent_config is replaced by two callbacks:

.unregister - this is called upon removing the device and
it unregisters the entity. This is an optional callback since
subdevices don't need to implement it because they are already
unregistered in v4l2_device_unregister.

.release - this is called from the release callback of v4l2_device
and it frees the entity.

This ensures that the entities will be released when the last fh
of any of the devices is closed.

The commands that cause the crash and the KASAN report:

media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440
v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
v4l2-ctl --stream-mmap --stream-count=1000 -d /dev/video2 &
sleep 1
echo -n vimc.0 >/sys/bus/platform/drivers/vimc/unbind

[  188.417934] BUG: KASAN: use-after-free in vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
[  188.420182] Read of size 8 at addr ffff8881e9c26008 by task bash/185
[  188.421800]
[  188.422223] CPU: 0 PID: 185 Comm: bash Not tainted 5.5.0-rc1+ #1
[  188.423681] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[  188.425938] Call Trace:
[  188.426610]  dump_stack+0x75/0xa0
[  188.427519]  ? vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
[  188.429057]  print_address_description.constprop.6+0x16/0x220
[  188.430462]  ? vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
[  188.431979]  ? vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
[  188.433455]  __kasan_report.cold.9+0x1a/0x40
[  188.434518]  ? vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
[  188.436010]  kasan_report+0xe/0x20
[  188.436859]  vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
[  188.438339]  vimc_streamer_s_stream+0x8b/0x3c0 [vimc]
[  188.439576]  vimc_cap_stop_streaming+0x22/0x40 [vimc]
[  188.440863]  __vb2_queue_cancel+0x65/0x560 [videobuf2_common]
[  188.442391]  vb2_core_queue_release+0x19/0x50 [videobuf2_common]
[  188.443974]  vimc_cap_rm+0x10/0x20 [vimc]
[  188.444986]  vimc_rm_subdevs+0x9e/0xe0 [vimc]
[  188.446179]  vimc_remove+0x19/0x70 [vimc]
[  188.447301]  platform_drv_remove+0x2f/0x50
[  188.448468]  device_release_driver_internal+0x133/0x260
[  188.449814]  unbind_store+0x121/0x150
[  188.450726]  kernfs_fop_write+0x142/0x230
[  188.451724]  ? sysfs_kf_bin_read+0x100/0x100
[  188.452826]  vfs_write+0xdc/0x230
[  188.453760]  ksys_write+0xaf/0x140
[  188.454702]  ? __ia32_sys_read+0x40/0x40
[  188.455773]  ? __do_page_fault+0x473/0x620
[  188.456780]  do_syscall_64+0x5e/0x1a0
[  188.457711]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  188.459079] RIP: 0033:0x7f80f1f13504
[  188.459969] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 48 8d 05 f9 61 0d 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 41 54 49 89 d4 55 48 89 f5 53
[  188.464445] RSP: 002b:00007ffd7e843b58 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  188.466276] RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00007f80f1f13504
[  188.467999] RDX: 0000000000000006 RSI: 000055ef2eb21b10 RDI: 0000000000000001
[  188.469708] RBP: 000055ef2eb21b10 R08: 00007f80f1fe68c0 R09: 00007f80f1e26740
[  188.471407] R10: 000055ef2eade010 R11: 0000000000000246 R12: 00007f80f1fe5760
[  188.473381] R13: 0000000000000006 R14: 00007f80f1fe0760 R15: 0000000000000006
[  188.475107]
[  188.475500] Allocated by task 473:
[  188.476351]  save_stack+0x19/0x80
[  188.477201]  __kasan_kmalloc.constprop.6+0xc1/0xd0
[  188.478507]  vimc_sen_add+0x36/0x309 [vimc]
[  188.479649]  vimc_probe+0x1e2/0x530 [vimc]
[  188.480776]  platform_drv_probe+0x46/0xa0
[  188.481829]  really_probe+0x16c/0x520
[  188.482732]  driver_probe_device+0x114/0x170
[  188.483783]  device_driver_attach+0x85/0x90
[  188.484800]  __driver_attach+0xa8/0x190
[  188.485734]  bus_for_each_dev+0xe4/0x140
[  188.486702]  bus_add_driver+0x223/0x2d0
[  188.487715]  driver_register+0xca/0x140
[  188.488767]  0xffffffffc037003d
[  188.489635]  do_one_initcall+0x86/0x28f
[  188.490702]  do_init_module+0xf8/0x340
[  188.491773]  load_module+0x3766/0x3a10
[  188.492811]  __do_sys_finit_module+0x11a/0x1b0
[  188.494059]  do_syscall_64+0x5e/0x1a0
[  188.495079]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  188.496481]
[  188.496893] Freed by task 185:
[  188.497670]  save_stack+0x19/0x80
[  188.498493]  __kasan_slab_free+0x125/0x170
[  188.499486]  kfree+0x8c/0x230
[  188.500254]  v4l2_subdev_release+0x64/0x70 [videodev]
[  188.501498]  v4l2_device_release_subdev_node+0x1c/0x30 [videodev]
[  188.502976]  device_release+0x3c/0xd0
[  188.503867]  kobject_put+0xf4/0x240
[  188.507802]  vimc_rm_subdevs+0x9e/0xe0 [vimc]
[  188.508846]  vimc_remove+0x19/0x70 [vimc]
[  188.509792]  platform_drv_remove+0x2f/0x50
[  188.510752]  device_release_driver_internal+0x133/0x260
[  188.512006]  unbind_store+0x121/0x150
[  188.512899]  kernfs_fop_write+0x142/0x230
[  188.513874]  vfs_write+0xdc/0x230
[  188.514698]  ksys_write+0xaf/0x140
[  188.515523]  do_syscall_64+0x5e/0x1a0
[  188.516543]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  188.517710]
[  188.518034] The buggy address belongs to the object at ffff8881e9c26000
[  188.518034]  which belongs to the cache kmalloc-4k of size 4096
[  188.520528] The buggy address is located 8 bytes inside of
[  188.520528]  4096-byte region [ffff8881e9c26000, ffff8881e9c27000)
[  188.523015] The buggy address belongs to the page:
[  188.524357] page:ffffea0007a70800 refcount:1 mapcount:0 mapping:ffff8881f6402140 index:0x0 compound_mapcount: 0
[  188.527058] raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881f6402140
[  188.528983] raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
[  188.530883] page dumped because: kasan: bad access detected
[  188.532336]
[  188.532720] Memory state around the buggy address:
[  188.533871]  ffff8881e9c25f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  188.535631]  ffff8881e9c25f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  188.537370] >ffff8881e9c26000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  188.538996]                       ^
[  188.539812]  ffff8881e9c26080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  188.541549]  ffff8881e9c26100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>