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CVE-2024-50278: dm cache: fix potential out-of-bounds access on the first resume

7.1 CVSS

Description

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

dm cache: fix potential out-of-bounds access on the first resume

Out-of-bounds access occurs if the fast device is expanded unexpectedly
before the first-time resume of the cache table. This happens because
expanding the fast device requires reloading the cache table for
cache_create to allocate new in-core data structures that fit the new
size, and the check in cache_preresume is not performed during the
first resume, leading to the issue.

Reproduce steps:

1. prepare component devices:

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 65536 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

2. load a cache table of 512 cache blocks, and deliberately expand the
fast device before resuming the cache, making the in-core data
structures inadequate.

dmsetup create cache --notable
dmsetup reload cache --table "0 524288 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"
dmsetup reload cdata --table "0 131072 linear /dev/sdc 8192"
dmsetup resume cdata
dmsetup resume cache

3. suspend the cache to write out the in-core dirty bitset and hint
array, leading to out-of-bounds access to the dirty bitset at offset
0x40:

dmsetup suspend cache

KASAN reports:

BUG: KASAN: vmalloc-out-of-bounds in is_dirty_callback+0x2b/0...

Classification

CVE ID: CVE-2024-50278

CVSS Base Severity: HIGH

CVSS Base Score: 7.1

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 11.62% (scored less or equal to compared to others)

EPSS Date: 2025-06-02 (when was this score calculated)

References

Timeline

2025-03-06 09:45:35 UTC
Tenable Plugins

Linux Distros Unpatched Vulnerability : CVE-2024-50278
2025-05-04 10:40:22 UTC
CVE

dm cache: fix potential out-of-bounds access on the first resume