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Description

In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs: check contexts->nr in repeat_call_fn damon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(), damon_sysfs_upd_schemes_stats(), and damon_sysfs_upd_schemes_effective_quotas() without checking contexts->nr. If nr_contexts is set to 0 via sysfs while DAMON is running, these functions dereference contexts_arr[0] and cause a NULL pointer dereference. Add the missing check. For example, the issue can be reproduced using DAMON sysfs interface and DAMON user-space tool (damo) [1] like below. $ sudo damo start --refresh_interval 1s $ echo 0 | sudo tee \ /sys/kernel/mm/damon/admin/kdamonds/0/contexts/nr_contexts

PUBLISHED Reserved 2026-03-09 | Published 2026-04-22 | Updated 2026-04-22 | Assigner Linux

Product status

Default status
unaffected

d809a7c64ba8229286b333c0cba03b1cdfb50238 (git) before 3527e9fdc38570cea0f6ddb7a2c9303d4044b217
affected

d809a7c64ba8229286b333c0cba03b1cdfb50238 (git) before 652cd0641a763dd0e846b0d12814977fadb2b7d8
affected

d809a7c64ba8229286b333c0cba03b1cdfb50238 (git) before 6557004a8b59c7701e695f02be03c7e20ed1cc15
affected

Default status
affected

6.17
affected

Any version before 6.17
unaffected

6.18.21 (semver)
unaffected

6.19.11 (semver)
unaffected

7.0 (original_commit_for_fix)
unaffected

References

git.kernel.org/...c/3527e9fdc38570cea0f6ddb7a2c9303d4044b217

git.kernel.org/...c/652cd0641a763dd0e846b0d12814977fadb2b7d8

git.kernel.org/...c/6557004a8b59c7701e695f02be03c7e20ed1cc15

cve.org (CVE-2026-31457)

nvd.nist.gov (CVE-2026-31457)

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