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Lin Ma cb6c99aedd hamradio: defer ax25 kfree after unregister_netdev 
commit 3e0588c291 upstream.

There is a possible race condition (use-after-free) like below

 (USE)                       |  (FREE)
ax25_sendmsg                 |
 ax25_queue_xmit             |
  dev_queue_xmit             |
   __dev_queue_xmit          |
    __dev_xmit_skb           |
     sch_direct_xmit         | ...
      xmit_one               |
       netdev_start_xmit     | tty_ldisc_kill
        __netdev_start_xmit  |  mkiss_close
         ax_xmit             |   kfree
          ax_encaps          |
                             |

Even though there are two synchronization primitives before the kfree:
1. wait_for_completion(&ax->dead). This can prevent the race with
routines from mkiss_ioctl. However, it cannot stop the routine coming
from upper layer, i.e., the ax25_sendmsg.

2. netif_stop_queue(ax->dev). It seems that this line of code aims to
halt the transmit queue but it fails to stop the routine that already
being xmit.

This patch reorder the kfree after the unregister_netdev to avoid the
possible UAF as the unregister_netdev() is well synchronized and won't
return if there is a running routine.

Signed-off-by: Lin Ma <linma@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-12-29 12:29:02 +01:00
arch arm64: dts: lx2160a: fix scl-gpios property name 2021-12-29 12:28:59 +01:00
block iocost: Fix divide-by-zero on donation from low hweight cgroup 2021-12-22 09:32:48 +01:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto crypto: pcrypt - Delay write to padata->info 2021-11-18 19:16:44 +01:00
Documentation KVM: VMX: Fix stale docs for kvm-intel.emulate_invalid_guest_state 2021-12-29 12:28:59 +01:00
drivers hamradio: defer ax25 kfree after unregister_netdev 2021-12-29 12:29:02 +01:00
fs netfs: fix parameter of cleanup() 2021-12-29 12:28:59 +01:00
include tee: handle lookup of shm with reference count 0 2021-12-29 12:28:54 +01:00
init init: make unknown command line param message clearer 2021-11-18 19:17:11 +01:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-25 09:48:42 +01:00
kernel kernel/crash_core: suppress unknown crashkernel parameter warning 2021-12-29 12:28:49 +01:00
lib siphash: use _unaligned version by default 2021-12-08 09:04:47 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm kfence: fix memory leak when cat kfence objects 2021-12-29 12:29:00 +01:00
net ax25: NPD bug when detaching AX25 device 2021-12-29 12:29:02 +01:00
samples samples/bpf: Fix incorrect use of strlen in xdp_redirect_cpu 2021-11-25 09:48:33 +01:00
scripts recordmcount.pl: look for jgnop instruction as well as bcrl on s390 2021-12-22 09:32:36 +01:00
security selinux: fix sleeping function called from invalid context 2021-12-22 09:32:47 +01:00
sound ASoC: rt5682: fix the wrong jack type detected 2021-12-29 12:29:01 +01:00
tools selftests: KVM: Fix non-x86 compiling 2021-12-29 12:28:37 +01:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: downgrade two BUG_ONs to WARN_ON_ONCE 2021-12-22 09:32:34 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
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 drm fixes for 5.15 final 2021-10-28 12:17:01 -07:00
Makefile Linux 5.15.11 2021-12-22 09:32:52 +01:00
README

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.