CVE-2021-47517 Affecting kernel-macros package, versions <5.14.21-150500.55.80.2


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.05% (18th percentile)

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  • Snyk IDSNYK-SLES155-KERNELMACROS-8103312
  • published28 Sept 2024
  • disclosed27 Sept 2024

Introduced: 27 Sep 2024

CVE-2021-47517  (opens in a new tab)

How to fix?

Upgrade SLES:15.5 kernel-macros to version 5.14.21-150500.55.80.2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-macros package and not the kernel-macros package as distributed by SLES. See How to fix? for SLES:15.5 relevant fixed versions and status.

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

ethtool: do not perform operations on net devices being unregistered

There is a short period between a net device starts to be unregistered and when it is actually gone. In that time frame ethtool operations could still be performed, which might end up in unwanted or undefined behaviours[1].

Do not allow ethtool operations after a net device starts its unregistration. This patch targets the netlink part as the ioctl one isn't affected: the reference to the net device is taken and the operation is executed within an rtnl lock section and the net device won't be found after unregister.

[1] For example adding Tx queues after unregister ends up in NULL pointer exceptions and UaFs, such as:

  BUG: KASAN: use-after-free in kobject_get+0x14/0x90
  Read of size 1 at addr ffff88801961248c by task ethtool/755

CPU: 0 PID: 755 Comm: ethtool Not tainted 5.15.0-rc6+ #778 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/014 Call Trace: dump_stack_lvl+0x57/0x72 print_address_description.constprop.0+0x1f/0x140 kasan_report.cold+0x7f/0x11b kobject_get+0x14/0x90 kobject_add_internal+0x3d1/0x450 kobject_init_and_add+0xba/0xf0 netdev_queue_update_kobjects+0xcf/0x200 netif_set_real_num_tx_queues+0xb4/0x310 veth_set_channels+0x1c3/0x550 ethnl_set_channels+0x524/0x610

CVSS Scores

version 3.1