Subject: CVE-2021-47220: usb: dwc3: core: fix kernel panic when do reboot

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

usb: dwc3: core: fix kernel panic when do reboot

When do system reboot, it calls dwc3_shutdown and the whole debugfs
for dwc3 has removed first, when the gadget tries to do deinit, and
remove debugfs for its endpoints, it meets NULL pointer dereference
issue when call debugfs_lookup. Fix it by removing the whole dwc3
debugfs later than dwc3_drd_exit.

[ 2924.958838] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000002
....
[ 2925.030994] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
[ 2925.037005] pc : inode_permission+0x2c/0x198
[ 2925.041281] lr : lookup_one_len_common+0xb0/0xf8
[ 2925.045903] sp : ffff80001276ba70
[ 2925.049218] x29: ffff80001276ba70 x28: ffff0000c01f0000 x27: 0000000000000000
[ 2925.056364] x26: ffff800011791e70 x25: 0000000000000008 x24: dead000000000100
[ 2925.063510] x23: dead000000000122 x22: 0000000000000000 x21: 0000000000000001
[ 2925.070652] x20: ffff8000122c6188 x19: 0000000000000000 x18: 0000000000000000
[ 2925.077797] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000004
[ 2925.084943] x14: ffffffffffffffff x13: 0000000000000000 x12: 0000000000000030
[ 2925.092087] x11: 0101010101010101 x10: 7f7f7f7f7f7f7f7f x9 : ffff8000102b2420
[ 2925.099232] x8 : 7f7f7f7f7f7f7f7f x7 : feff73746e2f6f64 x6 : 0000000000008080
[ 2925.106378] x5 : 61c8864680b583eb x4 : 209e6ec2d263dbb7 x3 : 000074756f307065
[ 2925.113523] x2 : 0000000000000001 x1 : 0000000000000000 x0 : ffff8000122c6188
[ 2925.120671] Call trace:
[ 2925.123119]  inode_permission+0x2c/0x198
[ 2925.127042]  lookup_one_len_common+0xb0/0xf8
[ 2925.131315]  lookup_one_len_unlocked+0x34/0xb0
[ 2925.135764]  lookup_positive_unlocked+0x14/0x50
[ 2925.140296]  debugfs_lookup+0x68/0xa0
[ 2925.143964]  dwc3_gadget_free_endpoints+0x84/0xb0
[ 2925.148675]  dwc3_gadget_exit+0x28/0x78
[ 2925.152518]  dwc3_drd_exit+0x100/0x1f8
[ 2925.156267]  dwc3_remove+0x11c/0x120
[ 2925.159851]  dwc3_shutdown+0x14/0x20
[ 2925.163432]  platform_shutdown+0x28/0x38
[ 2925.167360]  device_shutdown+0x15c/0x378
[ 2925.171291]  kernel_restart_prepare+0x3c/0x48
[ 2925.175650]  kernel_restart+0x1c/0x68
[ 2925.179316]  __do_sys_reboot+0x218/0x240
[ 2925.183247]  __arm64_sys_reboot+0x28/0x30
[ 2925.187262]  invoke_syscall+0x48/0x100
[ 2925.191017]  el0_svc_common.constprop.0+0x48/0xc8
[ 2925.195726]  do_el0_svc+0x28/0x88
[ 2925.199045]  el0_svc+0x20/0x30
[ 2925.202104]  el0_sync_handler+0xa8/0xb0
[ 2925.205942]  el0_sync+0x148/0x180
[ 2925.209270] Code: a9025bf5 2a0203f5 121f0056 370802b5 (79400660)
[ 2925.215372] ---[ end trace 124254d8e485a58b ]---
[ 2925.220012] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[ 2925.227676] Kernel Offset: disabled
[ 2925.231164] CPU features: 0x00001001,20000846
[ 2925.235521] Memory Limit: none
[ 2925.238580] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---

The Linux kernel CVE team has assigned CVE-2021-47220 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.14 with commit 5ff90af9da8f and fixed in 4.9.274 with commit ff4c63f3e8cb
	Issue introduced in 5.14 with commit 5ff90af9da8f and fixed in 4.14.238 with commit 58b5e02c6ca0
	Issue introduced in 5.14 with commit 5ff90af9da8f and fixed in 4.19.196 with commit 7f9745ab342b
	Issue introduced in 5.14 with commit 5ff90af9da8f and fixed in 5.4.128 with commit fd7c4bd58249
	Issue introduced in 5.14 with commit 5ff90af9da8f and fixed in 5.10.46 with commit 174c27583b38
	Issue introduced in 5.14 with commit 5ff90af9da8f and fixed in 5.12.13 with commit fa8c413e6b74

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47220
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/usb/dwc3/core.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/ff4c63f3e8cb7af2ce51cc56b031e08fd23c758b
	https://git.kernel.org/stable/c/58b5e02c6ca0e2b7c87cd8023ff786ef3c0eef74
	https://git.kernel.org/stable/c/7f9745ab342bcce5efd5d4d2297d0a3dd9db0eac
	https://git.kernel.org/stable/c/fd7c4bd582494934be15d41aebe0dbe23790605f
	https://git.kernel.org/stable/c/174c27583b3807ac96228c442735b02622d8d1c3
	https://git.kernel.org/stable/c/fa8c413e6b74ae5d12daf911c73238c5bdacd8e6
	https://git.kernel.org/stable/c/2a042767814bd0edf2619f06fecd374e266ea068