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Lin Ma fa78d2d1d6 Bluetooth: fix data races in smp_unregister(), smp_del_chan() 
Previous commit e04480920d ("Bluetooth: defer cleanup of resources
in hci_unregister_dev()") defers all destructive actions to
hci_release_dev() to prevent cocurrent problems like NPD, UAF.

However, there are still some exceptions that are ignored.

The smp_unregister() in hci_dev_close_sync() (previously in
hci_dev_do_close) will release resources like the sensitive channel
and the smp_dev objects. Consider the situations the device is detaching
or power down while the kernel is still operating on it, the following
data race could take place.

thread-A  hci_dev_close_sync  | thread-B  read_local_oob_ext_data
                              |
hci_dev_unlock()              |
...                           | hci_dev_lock()
if (hdev->smp_data)           |
  chan = hdev->smp_data       |
                              | chan = hdev->smp_data (3)
                              |
  hdev->smp_data = NULL (1)   | if (!chan || !chan->data) (4)
  ...                         |
  smp = chan->data            | smp = chan->data
  if (smp)                    |
    chan->data = NULL (2)     |
    ...                       |
    kfree_sensitive(smp)      |
                              | // dereference smp trigger UFA

That is, the objects hdev->smp_data and chan->data both suffer from the
data races. In a preempt-enable kernel, the above schedule (when (3) is
before (1) and (4) is before (2)) leads to UAF bugs. It can be
reproduced in the latest kernel and below is part of the report:

[   49.097146] ================================================================
[   49.097611] BUG: KASAN: use-after-free in smp_generate_oob+0x2dd/0x570
[   49.097611] Read of size 8 at addr ffff888006528360 by task generate_oob/155
[   49.097611]
[   49.097611] Call Trace:
[   49.097611]  <TASK>
[   49.097611]  dump_stack_lvl+0x34/0x44
[   49.097611]  print_address_description.constprop.0+0x1f/0x150
[   49.097611]  ? smp_generate_oob+0x2dd/0x570
[   49.097611]  ? smp_generate_oob+0x2dd/0x570
[   49.097611]  kasan_report.cold+0x7f/0x11b
[   49.097611]  ? smp_generate_oob+0x2dd/0x570
[   49.097611]  smp_generate_oob+0x2dd/0x570
[   49.097611]  read_local_oob_ext_data+0x689/0xc30
[   49.097611]  ? hci_event_packet+0xc80/0xc80
[   49.097611]  ? sysvec_apic_timer_interrupt+0x9b/0xc0
[   49.097611]  ? asm_sysvec_apic_timer_interrupt+0x12/0x20
[   49.097611]  ? mgmt_init_hdev+0x1c/0x240
[   49.097611]  ? mgmt_init_hdev+0x28/0x240
[   49.097611]  hci_sock_sendmsg+0x1880/0x1e70
[   49.097611]  ? create_monitor_event+0x890/0x890
[   49.097611]  ? create_monitor_event+0x890/0x890
[   49.097611]  sock_sendmsg+0xdf/0x110
[   49.097611]  __sys_sendto+0x19e/0x270
[   49.097611]  ? __ia32_sys_getpeername+0xa0/0xa0
[   49.097611]  ? kernel_fpu_begin_mask+0x1c0/0x1c0
[   49.097611]  __x64_sys_sendto+0xd8/0x1b0
[   49.097611]  ? syscall_exit_to_user_mode+0x1d/0x40
[   49.097611]  do_syscall_64+0x3b/0x90
[   49.097611]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   49.097611] RIP: 0033:0x7f5a59f51f64
...
[   49.097611] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5a59f51f64
[   49.097611] RDX: 0000000000000007 RSI: 00007f5a59d6ac70 RDI: 0000000000000006
[   49.097611] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[   49.097611] R10: 0000000000000040 R11: 0000000000000246 R12: 00007ffec26916ee
[   49.097611] R13: 00007ffec26916ef R14: 00007f5a59d6afc0 R15: 00007f5a59d6b700

To solve these data races, this patch places the smp_unregister()
function in the protected area by the hci_dev_lock(). That is, the
smp_unregister() function can not be concurrently executed when
operating functions (most of them are mgmt operations in mgmt.c) hold
the device lock.

This patch is tested with kernel LOCK DEBUGGING enabled. The price from
the extended holding time of the device lock is supposed to be low as the
smp_unregister() function is fairly short and efficient.

Signed-off-by: Lin Ma <linma@zju.edu.cn>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2022-02-24 21:05:21 +01:00
arch ARM: 2022-02-15 11:07:59 -08:00
block block: bio-integrity: Advance seed correctly for larger interval sizes 2022-02-03 21:09:24 -07:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto crypto: af_alg - get rid of alg_memory_allocated 2022-02-15 14:29:04 +00:00
Documentation Interrupt chip driver fixes: 2022-02-13 10:06:40 -08:00
drivers net: mv643xx_eth: process retval from of_get_mac_address 2022-02-24 10:05:08 -08:00
fs fs/file_table: fix adding missing kmemleak_not_leak() 2022-02-17 10:23:19 -08:00
include openvswitch: Fix setting ipv6 fields causing hw csum failure 2022-02-24 09:16:21 -08:00
init lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() 2022-01-22 08:33:37 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-04 09:25:05 -08:00
kernel Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2022-02-17 12:01:55 -08:00
lib lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI 2022-02-04 19:22:32 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: don't try to NUMA-migrate COW pages that have other uses 2022-02-17 08:57:47 -08:00
net Bluetooth: fix data races in smp_unregister(), smp_del_chan() 2022-02-24 21:05:21 +01:00
samples samples/seccomp: Adjust sample to also provide kill option 2022-02-10 19:09:12 -08:00
scripts kconfig: fix failing to generate auto.conf 2022-02-12 23:24:19 +09:00
security integrity-v5-17-fix 2022-02-07 09:55:14 -08:00
sound ASoC: Fixes for v5.17 2022-02-01 16:52:54 +01:00
tools selftests: mptcp: be more conservative with cookie MPJ limits 2022-02-19 12:28:01 +00:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt Two larger x86 series: 2022-01-28 19:00:26 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Christian Brauner's email address 2022-02-01 11:21:31 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Removing Ohad from remoteproc/rpmsg maintenance 2021-12-08 10:09:40 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add myself as co-maintainer for Realtek DSA switch drivers 2022-02-23 12:36:21 +00:00
Makefile Linux 5.17-rc4 2022-02-13 12:13:30 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.