KASAN: use-after-free Read in __media_entity_remove_links

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 4cc037ec usb: gadget: add raw-gadget interface
git tree: https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=104e177ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=e9c2b6de462bc469
dashboard link: https://syzkaller.appspot.com/bug?extid=0b0095300dfeb8a83dc8
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=117f2fb1e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16842d2ee00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+0b0095...@syzkaller.appspotmail.com

usb 1-1: USB disconnect, device number 2
==================================================================
BUG: KASAN: use-after-free in __media_entity_remove_links+0x134/0x160
drivers/media/mc/mc-entity.c:779
Read of size 8 at addr ffff8881d199f120 by task kworker/1:2/1719

CPU: 1 PID: 1719 Comm: kworker/1:2 Not tainted 5.5.0-rc1-syzkaller #0
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+0xef/0x16e lib/dump_stack.c:118
print_address_description.constprop.0+0x16/0x200 mm/kasan/report.c:374
__kasan_report.cold+0x37/0x7f mm/kasan/report.c:506
kasan_report+0xe/0x20 mm/kasan/common.c:639
__media_entity_remove_links+0x134/0x160 drivers/media/mc/mc-entity.c:779
__media_device_unregister_entity+0x187/0x300
drivers/media/mc/mc-device.c:596
media_device_unregister_entity+0x49/0x70 drivers/media/mc/mc-device.c:688
v4l2_device_unregister_subdev+0x257/0x380
drivers/media/v4l2-core/v4l2-device.c:283
v4l2_device_unregister drivers/media/v4l2-core/v4l2-device.c:100 [inline]
v4l2_device_unregister+0x139/0x220 drivers/media/v4l2-core/v4l2-device.c:88
uvc_unregister_video+0x11a/0x210 drivers/media/usb/uvc/uvc_driver.c:1929
uvc_disconnect+0xbc/0x160 drivers/media/usb/uvc/uvc_driver.c:2242
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x481/0xd30 drivers/base/core.c:2664
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200
hub_port_connect drivers/usb/core/hub.c:5035 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x1753/0x3860 drivers/usb/core/hub.c:5552
process_one_work+0x92b/0x1530 kernel/workqueue.c:2264
worker_thread+0x96/0xe20 kernel/workqueue.c:2410
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 22:
save_stack+0x1b/0x80 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
__kasan_kmalloc mm/kasan/common.c:513 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:486
kmalloc include/linux/slab.h:556 [inline]
kzalloc include/linux/slab.h:670 [inline]
media_add_link+0x47/0x180 drivers/media/mc/mc-entity.c:592
media_create_pad_link+0x1fb/0x530 drivers/media/mc/mc-entity.c:684
uvc_mc_create_links drivers/media/usb/uvc/uvc_entity.c:50 [inline]
uvc_mc_register_entities+0x468/0x77a drivers/media/usb/uvc/uvc_entity.c:114
uvc_register_chains drivers/media/usb/uvc/uvc_driver.c:2075 [inline]
uvc_probe.cold+0x2137/0x29de drivers/media/usb/uvc/uvc_driver.c:2201
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x104/0x210 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
device_add+0x1480/0x1c20 drivers/base/core.c:2487
usb_set_configuration+0xe67/0x1740 drivers/usb/core/message.c:2023
generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
really_probe+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x104/0x210 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
device_add+0x1480/0x1c20 drivers/base/core.c:2487
usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2537
hub_port_connect drivers/usb/core/hub.c:5184 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x1e59/0x3860 drivers/usb/core/hub.c:5552
process_one_work+0x92b/0x1530 kernel/workqueue.c:2264
worker_thread+0x96/0xe20 kernel/workqueue.c:2410
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 1719:
save_stack+0x1b/0x80 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
kasan_set_free_info mm/kasan/common.c:335 [inline]
__kasan_slab_free+0x129/0x170 mm/kasan/common.c:474
slab_free_hook mm/slub.c:1425 [inline]
slab_free_freelist_hook mm/slub.c:1458 [inline]
slab_free mm/slub.c:3005 [inline]
kfree+0xda/0x310 mm/slub.c:3957
__media_entity_remove_link+0x25c/0x5d0 drivers/media/mc/mc-entity.c:622
__media_entity_remove_links+0x86/0x160 drivers/media/mc/mc-entity.c:780
__media_device_unregister_entity+0x187/0x300
drivers/media/mc/mc-device.c:596
media_device_unregister_entity+0x49/0x70 drivers/media/mc/mc-device.c:688
v4l2_device_unregister_subdev+0x257/0x380
drivers/media/v4l2-core/v4l2-device.c:283
v4l2_device_unregister drivers/media/v4l2-core/v4l2-device.c:100 [inline]
v4l2_device_unregister+0x139/0x220 drivers/media/v4l2-core/v4l2-device.c:88
uvc_unregister_video+0x11a/0x210 drivers/media/usb/uvc/uvc_driver.c:1929
uvc_disconnect+0xbc/0x160 drivers/media/usb/uvc/uvc_driver.c:2242
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x481/0xd30 drivers/base/core.c:2664
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200
hub_port_connect drivers/usb/core/hub.c:5035 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x1753/0x3860 drivers/usb/core/hub.c:5552
process_one_work+0x92b/0x1530 kernel/workqueue.c:2264
worker_thread+0x96/0xe20 kernel/workqueue.c:2410
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8881d199f100
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 32 bytes inside of
96-byte region [ffff8881d199f100, ffff8881d199f160)
The buggy address belongs to the page:
page:ffffea00074667c0 refcount:1 mapcount:0 mapping:ffff8881da002f00
index:0xffff8881d199fe80
raw: 0200000000000200 ffffea0007474e40 0000000e0000000e ffff8881da002f00
raw: ffff8881d199fe80 0000000080200016 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881d199f000: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff8881d199f080: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
> ffff8881d199f100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff8881d199f180: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff8881d199f200: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[syzbot]

This bug is marked as fixed by commit:
media: uvcvideo: Avoid cyclic entity chains due to malformed

But I can't find it in the tested trees[1] for more than 90 days.
Is it a correct commit? Please update it by replying:

#syz fix: exact-commit-title

Until then the bug is still considered open and new crashes with
the same signature are ignored.

Kernel: Linux
Dashboard link: https://syzkaller.appspot.com/bug?extid=0b0095300dfeb8a83dc8

---
[1] I expect the commit to be present in:

1. for-kernelci branch of
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git

2. master branch of
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git

3. master branch of
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git

4. main branch of
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git

The full list of 9 trees can be found at
https://syzkaller.appspot.com/upstream/repos

[Laurent Pinchart]

On Tue, Jul 11, 2023 at 06:00:08AM -0700, syzbot wrote:
> This bug is marked as fixed by commit:
> media: uvcvideo: Avoid cyclic entity chains due to malformed
>
> But I can't find it in the tested trees[1] for more than 90 days.
> Is it a correct commit? Please update it by replying:

#syz fix: media: uvcvideo: Avoid cyclic entity chains due to malformed USB descriptors

Can a commit ID be used as well ?

> Until then the bug is still considered open and new crashes with
> the same signature are ignored.
>
> Kernel: Linux
> Dashboard link: https://syzkaller.appspot.com/bug?extid=0b0095300dfeb8a83dc8
>
> ---
> [1] I expect the commit to be present in:
>
> 1. for-kernelci branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
>
> 2. master branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
>
> 3. master branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
>
> 4. main branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
>
> The full list of 9 trees can be found at
> https://syzkaller.appspot.com/upstream/repos

--
Regards,

Laurent Pinchart

[Aleksandr Nogikh]

On Wed, Jul 12, 2023 at 11:11 PM Laurent Pinchart
<laurent....@ideasonboard.com> wrote:
>
> On Tue, Jul 11, 2023 at 06:00:08AM -0700, syzbot wrote:
> > This bug is marked as fixed by commit:
> > media: uvcvideo: Avoid cyclic entity chains due to malformed
> >
> > But I can't find it in the tested trees[1] for more than 90 days.
> > Is it a correct commit? Please update it by replying:
>
> #syz fix: media: uvcvideo: Avoid cyclic entity chains due to malformed USB descriptors

Thanks for providing the correct name!

>
> Can a commit ID be used as well ?

The problem with commit hashes is that we fuzz quite a number of
different Linux trees and every new commit might appear in all of them
with totally different hashes. Name is a much more reliable
identifier, so that's what we currently require in #syz fix.

[syzbot]

This bug is marked as fixed by commit:

media: uvcvideo: Avoid cyclic entity chains due to malformed USB descriptors

But I can't find it in the tested trees[1] for more than 90 days.
Is it a correct commit? Please update it by replying:

#syz fix: exact-commit-title

[syzbot]

[syzbot]

[syzbot]

[Laurent Pinchart]

On Tue, Nov 21, 2023 at 01:13:15PM -0800, syzbot wrote:
> This bug is marked as fixed by commit:
> media: uvcvideo: Avoid cyclic entity chains due to malformed USB descriptors
>
> But I can't find it in the tested trees[1] for more than 90 days.
> Is it a correct commit? Please update it by replying:
>
> #syz fix: exact-commit-title

What logic does syzbot use to try and find the commit upstream ? There's
a commit with the exact same subject, what was missing to find it
automatically ?

> Until then the bug is still considered open and new crashes with
> the same signature are ignored.
>
> Kernel: Linux
> Dashboard link: https://syzkaller.appspot.com/bug?extid=0b0095300dfeb8a83dc8
>
> ---
> [1] I expect the commit to be present in:
>
> 1. for-kernelci branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
>
> 2. master branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
>
> 3. master branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
>
> 4. main branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
>
> The full list of 9 trees can be found at
> https://syzkaller.appspot.com/upstream/repos

--
Regards,

Laurent Pinchart

[Aleksandr Nogikh]

Thanks for reporting the problem!

Syzbot looked at the last ~1.5 years of commit history to find the
commit, which is almost always enough, but not in this particular
case.

I've filed https://github.com/google/syzkaller/issues/4347 to fix the
syzbot code.

--
Aleksandr

[syzbot]

This bug is marked as fixed by commit:
media: uvcvideo: Avoid cyclic entity chains due to malformed USB descriptors

But I can't find it in the tested trees[1] for more than 90 days.
Is it a correct commit? Please update it by replying:

#syz fix: exact-commit-title

[syzbot]