CVE-2024-50279

/// Technical 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"

2. 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

dmset

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References