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CVE-2024-50279

Disclosure Date: November 19, 2024 •
CVE-2024-50279
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

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.

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CVSS V3 Severity and Metrics
Base Score:
None
Impact Score:
Unknown
Exploitability Score:
Unknown
Vector:
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Attack Vector (AV):
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Attack Complexity (AC):
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General Information

Offensive Application
Unknown
Utility Class
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Ports
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OS
Unknown
Vulnerable Versions
Linux 4fa4feb873ce
Linux not down converted
Prerequisites
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Discovered By
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PoC Author
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Metasploit Module
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Reporter
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Vendors

  • Linux

Products

  • Linux
Technical Analysis