Subject: CVE-2021-47237: net: hamradio: fix memory leak in mkiss_close

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

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

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

net: hamradio: fix memory leak in mkiss_close

My local syzbot instance hit memory leak in
mkiss_open()[1]. The problem was in missing
free_netdev() in mkiss_close().

In mkiss_open() netdevice is allocated and then
registered, but in mkiss_close() netdevice was
only unregistered, but not freed.

Fail log:

BUG: memory leak
unreferenced object 0xffff8880281ba000 (size 4096):
  comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s)
  hex dump (first 32 bytes):
    61 78 30 00 00 00 00 00 00 00 00 00 00 00 00 00  ax0.............
    00 27 fa 2a 80 88 ff ff 00 00 00 00 00 00 00 00  .'.*............
  backtrace:
    [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0
    [<ffffffff8706e7e8>] alloc_netdev_mqs+0x98/0xe80
    [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1]
    [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110
    [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670
    [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440
    [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200
    [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0
    [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

BUG: memory leak
unreferenced object 0xffff8880141a9a00 (size 96):
  comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s)
  hex dump (first 32 bytes):
    e8 a2 1b 28 80 88 ff ff e8 a2 1b 28 80 88 ff ff  ...(.......(....
    98 92 9c aa b0 40 02 00 00 00 00 00 00 00 00 00  .....@..........
  backtrace:
    [<ffffffff8709f68b>] __hw_addr_create_ex+0x5b/0x310
    [<ffffffff8709fb38>] __hw_addr_add_ex+0x1f8/0x2b0
    [<ffffffff870a0c7b>] dev_addr_init+0x10b/0x1f0
    [<ffffffff8706e88b>] alloc_netdev_mqs+0x13b/0xe80
    [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1]
    [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110
    [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670
    [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440
    [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200
    [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0
    [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

BUG: memory leak
unreferenced object 0xffff8880219bfc00 (size 512):
  comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s)
  hex dump (first 32 bytes):
    00 a0 1b 28 80 88 ff ff 80 8f b1 8d ff ff ff ff  ...(............
    80 8f b1 8d ff ff ff ff 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0
    [<ffffffff8706eec7>] alloc_netdev_mqs+0x777/0xe80
    [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1]
    [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110
    [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670
    [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440
    [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200
    [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0
    [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

BUG: memory leak
unreferenced object 0xffff888029b2b200 (size 256):
  comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0
    [<ffffffff8706f062>] alloc_netdev_mqs+0x912/0xe80
    [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1]
    [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110
    [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670
    [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440
    [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200
    [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0
    [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

The Linux kernel CVE team has assigned CVE-2021-47237 to this issue.

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

	Issue introduced in 2.6.14 with commit 815f62bf7427 and fixed in 4.4.274 with commit c634ba0b4159
	Issue introduced in 2.6.14 with commit 815f62bf7427 and fixed in 4.9.274 with commit 3942d0f9ace1
	Issue introduced in 2.6.14 with commit 815f62bf7427 and fixed in 4.14.238 with commit 765a8a04f828
	Issue introduced in 2.6.14 with commit 815f62bf7427 and fixed in 4.19.196 with commit c16c4716a1b5
	Issue introduced in 2.6.14 with commit 815f62bf7427 and fixed in 5.4.128 with commit a49cbb762ef2
	Issue introduced in 2.6.14 with commit 815f62bf7427 and fixed in 5.10.46 with commit 290b0b6432e2
	Issue introduced in 2.6.14 with commit 815f62bf7427 and fixed in 5.12.13 with commit f4de2b43d13b
	Issue introduced in 2.6.14 with commit 815f62bf7427 and fixed in 5.13 with commit 7edcc6823014

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-2021-47237
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/net/hamradio/mkiss.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/c634ba0b4159838ff45a60d3a0ace3b4118077a5
	https://git.kernel.org/stable/c/3942d0f9ace1a95a74930b5b4fc0e5005c62b37b
	https://git.kernel.org/stable/c/765a8a04f828db7222b36a42b1031f576bfe95c3
	https://git.kernel.org/stable/c/c16c4716a1b5ba4f83c7e00da457cba06761f119
	https://git.kernel.org/stable/c/a49cbb762ef20655f5c91abdc13658b0af5e159d
	https://git.kernel.org/stable/c/290b0b6432e2599021db0b8d6046f756d931c29f
	https://git.kernel.org/stable/c/f4de2b43d13b7cf3ced9310e371b90c836dbd7cd
	https://git.kernel.org/stable/c/7edcc682301492380fbdd604b4516af5ae667a13