CVE-2026-74643
Received Received - Intake

Division by Zero in Linux Kernel DAMON Sample Module

Publication date: 2026-08-22

Last updated on: 2026-08-22

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: samples/damon/mtier: error out for zero quota goal target values Patch series "mm/damon: avoid division by zero from damos_quota_score()". DAMON_SAMPLE_MTIER and DAMON_LRU_SORT allow the user to trigger division by zero in damos_quota_score(). Avoid it by adding parameters validation checks. This patch (of 2): damos_quota_score() can trigger division by zero if the target_value is zero. DAMON_SAMPLE_MTIER lets users set the target_value via node0_mem_{used,free}_bp parameters. It doesn't guard zero value case, though. As a result, users can trigger division by zero. Fix the issue by returning an error when the user tries to start DAMON with zero node0_mem_{used,free}_bp parameter values. DAMON_SAMPLE_MTIER is just a sample module, but the consequence is quite bad. Also the zero node0_mem_free_bp parameter might look like a reasonable setup to some users. Hence, the issue might really happen in the real world. One reliable way to reproduce the issue is like below: # cd /sys/module/damon_sample_mtier/parameters # echo 4096 > node0_start_addr # echo 8192 > node0_end_addr # echo 8192 > node1_start_addr # echo 81920 > node1_end_addr # echo 0 > node0_mem_free_bp # echo Y > enabled # dmesg -w [...] [18792.235916] Oops: divide error: 0000 [#1] SMP NOPTI [...] [18792.242787] RIP: 0010:damos_quota_score+0x6f/0x480 [...] This issue was discovered [1] by Sashiko.

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Meta Information

Published
2026-08-22
Last Modified
2026-08-22
Generated
2026-08-22
AI Q&A
2026-08-22
EPSS Evaluated
N/A
NVD
CVE-2026-74643
EUVD
EUVD-2026-64580

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a division by zero error in the DAMON memory management subsystem. Specifically, the damos_quota_score() function can trigger a division by zero if the target_value parameter is set to zero. This occurs in the DAMON_SAMPLE_MTIER and DAMON_LRU_SORT modules, which allow users to set target values via parameters like node0_mem_free_bp. The lack of validation for zero values enables this issue.

Detection Guidance

To detect this vulnerability, check if the DAMON_SAMPLE_MTIER module is enabled and if zero values are set for node0_mem_free_bp or node0_mem_used_bp parameters. Run: cd /sys/module/damon_sample_mtier/parameters; cat node0_mem_free_bp; cat node0_mem_used_bp. If zero values are present and the module is enabled, the system is vulnerable.

Impact Analysis

This vulnerability can cause a kernel crash (Oops) due to a divide error, leading to system instability or denial of service. Attackers with local access could exploit this to trigger a kernel panic by setting specific parameters to zero. While DAMON_SAMPLE_MTIER is a sample module, the issue could still occur in real-world setups if users configure zero values unintentionally.

Mitigation Strategies

Disable the DAMON_SAMPLE_MTIER module if not in use. If enabled, ensure node0_mem_free_bp and node0_mem_used_bp parameters are set to non-zero values. Update the Linux kernel to a patched version where this issue is resolved.

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