5.5

CVE-2026-31457

mm/damon/sysfs: check contexts->nr in repeat_call_fn

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
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version >= 6.17 < 6.18.21
Linux ≫ Linux Kernel Version >= 6.19 < 6.19.11
Linux ≫ Linux Kernel Version7.0 Updaterc1
Linux ≫ Linux Kernel Version7.0 Updaterc2
Linux ≫ Linux Kernel Version7.0 Updaterc3
Linux ≫ Linux Kernel Version7.0 Updaterc4
Linux ≫ Linux Kernel Version7.0 Updaterc5
VulnDex Vulnerability Enrichment
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.12% 0.022
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
nvd@nist.gov 5.5 1.8 3.6
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE-476 NULL Pointer Dereference

The product dereferences a pointer that it expects to be valid but is NULL.

https://git.kernel.org/stable/c/3527e9fdc38570cea0f6ddb7a2c9303d4044b217
Patch
https://git.kernel.org/stable/c/652cd0641a763dd0e846b0d12814977fadb2b7d8
Patch
https://git.kernel.org/stable/c/6557004a8b59c7701e695f02be03c7e20ed1cc15
Patch