CVE-2026-31458
mm/damon/sysfs: check contexts->nr before accessing contexts_arr[0]
In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs: check contexts->nr before accessing contexts_arr[0] Multiple sysfs command paths dereference contexts_arr[0] without first verifying that kdamond->contexts->nr == 1. A user can set nr_contexts to 0 via sysfs while DAMON is running, causing NULL pointer dereferences. In more detail, the issue can be triggered by privileged users like below. First, start DAMON and make contexts directory empty (kdamond->contexts->nr == 0). # damo start # cd /sys/kernel/mm/damon/admin/kdamonds/0 # echo 0 > contexts/nr_contexts Then, each of below commands will cause the NULL pointer dereference. # echo update_schemes_stats > state # echo update_schemes_tried_regions > state # echo update_schemes_tried_bytes > state # echo update_schemes_effective_quotas > state # echo update_tuned_intervals > state Guard all commands (except OFF) at the entry point of damon_sysfs_handle_cmd().
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7; < aba546061341b56e9ffb37e1eb661a3628b6ec12 (affected, git) ≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7; < 1e8da792672481d603fa7cd0d815577220a3ee27 (affected, git) ≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7; < 708033c231bd782858f4ddbb46ee874a5a5fbdab (affected, git) ≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7; < bbe03ad3fb9e714191757ca7b41582f930be7be2 (affected, git) ≥ 0ac32b8affb5a384253dbb8339bd2d0e91add0b7; < 1bfe9fb5ed2667fb075682408b776b5273162615 (affected, git) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
5.18 (affected) ≥ 0; < 5.18 (unaffected, semver) ≥ 6.6.131; ≤ 6.6.* (unaffected, semver) ≥ 6.12.80; ≤ 6.12.* (unaffected, semver) ≥ 6.18.21; ≤ 6.18.* (unaffected, semver) ≥ 6.19.11; ≤ 6.19.* (unaffected, semver) ≥ 7.0; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/aba546061341b56e9ffb37e1eb661a3628b6ec12CNA: Linux
- https://git.kernel.org/stable/c/1e8da792672481d603fa7cd0d815577220a3ee27CNA: Linux
- https://git.kernel.org/stable/c/708033c231bd782858f4ddbb46ee874a5a5fbdabCNA: Linux
- https://git.kernel.org/stable/c/bbe03ad3fb9e714191757ca7b41582f930be7be2CNA: Linux
- https://git.kernel.org/stable/c/1bfe9fb5ed2667fb075682408b776b5273162615CNA: Linux
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