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Duoming Zhou a54bf862cc net: usb: lan78xx: reorder cleanup operations to avoid UAF bugs 
[ Upstream commit 1e7417c188 ]

The timer dev->stat_monitor can schedule the delayed work dev->wq and
the delayed work dev->wq can also arm the dev->stat_monitor timer.

When the device is detaching, the net_device will be deallocated. but
the net_device private data could still be dereferenced in delayed work
or timer handler. As a result, the UAF bugs will happen.

One racy situation is shown below:

      (Thread 1)                 |      (Thread 2)
lan78xx_stat_monitor()           |
 ...                             |  lan78xx_disconnect()
 lan78xx_defer_kevent()          |    ...
  ...                            |    cancel_delayed_work_sync(&dev->wq);
  schedule_delayed_work()        |    ...
  (wait some time)               |    free_netdev(net); //free net_device
  lan78xx_delayedwork()          |
  //use net_device private data  |
  dev-> //use                    |

Although we use cancel_delayed_work_sync() to cancel the delayed work
in lan78xx_disconnect(), it could still be scheduled in timer handler
lan78xx_stat_monitor().

Another racy situation is shown below:

      (Thread 1)                |      (Thread 2)
lan78xx_delayedwork             |
 mod_timer()                    |  lan78xx_disconnect()
                                |   cancel_delayed_work_sync()
 (wait some time)               |   if (timer_pending(&dev->stat_monitor))
             	                |       del_timer_sync(&dev->stat_monitor);
 lan78xx_stat_monitor()         |   ...
  lan78xx_defer_kevent()        |   free_netdev(net); //free
   //use net_device private data|
   dev-> //use                  |

Although we use del_timer_sync() to delete the timer, the function
timer_pending() returns 0 when the timer is activated. As a result,
the del_timer_sync() will not be executed and the timer could be
re-armed.

In order to mitigate this bug, We use timer_shutdown_sync() to shutdown
the timer and then use cancel_delayed_work_sync() to cancel the delayed
work. As a result, the net_device could be deallocated safely.

What's more, the dev->flags is set to EVENT_DEV_DISCONNECT in
lan78xx_disconnect(). But it could still be set to EVENT_STAT_UPDATE
in lan78xx_stat_monitor(). So this patch put the set_bit() behind
timer_shutdown_sync().

Fixes: 77dfff5bb7 ("lan78xx: Fix race condition in disconnect handling")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-08-11 12:14:14 +02:00
arch KVM: s390: fix sthyi error handling 2023-08-11 12:14:08 +02:00
block blk-mq: Fix stall due to recursive flush plug 2023-08-03 10:25:41 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:36:19 +02:00
Documentation iommu/arm-smmu-v3: Document nesting-related errata 2023-08-11 12:14:05 +02:00
drivers net: usb: lan78xx: reorder cleanup operations to avoid UAF bugs 2023-08-11 12:14:14 +02:00
fs erofs: fix wrong primary bvec selection on deduplicated extents 2023-08-11 12:14:08 +02:00
include net: annotate data-races around sk->sk_mark 2023-08-11 12:14:13 +02:00
init init, x86: Move mem_encrypt_init() into arch_cpu_finalize_init() 2023-08-08 20:04:49 +02:00
io_uring io_uring: gate iowait schedule on having pending requests 2023-08-03 10:26:10 +02:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel locking/rtmutex: Fix task->pi_waiters integrity 2023-08-03 10:26:09 +02:00
lib lib/bitmap: workaround const_eval test build failure 2023-08-11 12:14:07 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: lock_vma_under_rcu() must check vma->anon_vma under vma lock 2023-08-11 12:14:05 +02:00
net net/sched: taprio: Limit TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME to INT_MAX. 2023-08-11 12:14:14 +02:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:54:09 +02:00
scripts kbuild: rust: avoid creating temporary files 2023-07-27 08:57:06 +02:00
security security: keys: Modify mismatched function name 2023-07-27 08:56:59 +02:00
sound ASoC: wm8904: Fill the cache for WM8904_ADC_TEST_0 register 2023-08-03 10:26:12 +02:00
tools net/sched: taprio: Limit TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME to INT_MAX. 2023-08-11 12:14:14 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:26:01 +02:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Ben Dooks 2023-06-19 13:19:35 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
Makefile Linux 6.4.9 2023-08-08 20:04:53 +02:00
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.