Out-of-bounds Read Affecting kernel-uki-virt-addons package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (15th percentile)

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  • Snyk IDSNYK-RHEL9-KERNELUKIVIRTADDONS-8425406
  • published27 Nov 2024
  • disclosed19 Nov 2024

Introduced: 19 Nov 2024

NewCVE-2024-50279  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-uki-virt-addons.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-uki-virt-addons package and not the kernel-uki-virt-addons package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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

dm cache: fix out-of-bounds access to the dirty bitset when resizing

dm-cache checks the dirty bits of the cache blocks to be dropped when shrinking the fast device, but an index bug in bitset iteration causes out-of-bounds access.

Reproduce steps:

  1. create a cache device of 1024 cache blocks (128 bytes dirty bitset)

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"

  1. shrink the fast device to 512 cache blocks, triggering out-of-bounds access to the dirty bitset (offset 0x80)

dmsetup suspend cache dmsetup reload cdata --table "0 65536 linear /dev/sdc 8192" dmsetup resume cdata dmsetup resume cache

KASAN reports:

BUG: KASAN: vmalloc-out-of-bounds in cache_preresume+0x269/0x7b0 Read of size 8 at addr ffffc900000f3080 by task dmsetup/131

(...snip...) The buggy address belongs to the virtual mapping at [ffffc900000f3000, ffffc900000f5000) created by: cache_ctr+0x176a/0x35f0

(...snip...) Memory state around the buggy address: ffffc900000f2f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900000f3000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffffc900000f3080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc900000f3100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900000f3180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8

Fix by making the index post-incremented.

CVSS Scores

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