CVE-2026-64036

cgroup/rstat: validate cpu before css_rstat_cpu() access

State: Published
Severity: 7.8 High
Published: Jul 19, 2026
Updated: Oct 30, 2026
Reserved: Jul 19, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

cgroup/rstat: validate cpu before css_rstat_cpu() access

css_rstat_updated() is exposed as a BPF kfunc and accepts a caller-provided cpu argument. The function uses cpu for per-cpu rstat lookups without checking whether it refers to a valid possible CPU.

A BPF iter/cgroup program with CAP_BPF and CAP_PERFMON can pass an invalid cpu value. On an unfixed UBSCAN_BOUNDS test kernel, cpu == 0x7fffffff triggers:

UBSAN: array-index-out-of-bounds in kernel/cgroup/rstat.c:31:9 index 2147483647 is out of range for type 'long unsigned int [64]' Call Trace: css_rstat_updated bpf_iter_run_prog cgroup_iter_seq_show bpf_seq_read

Add cpu validation to the BPF-facing css_rstat_updated() kfunc and move the common implementation to __css_rstat_updated() for in-kernel callers.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

CWE-125 Out-of-bounds Read

Affected Products

Product	Versions
LinuxLinux	a319185be9f5ad13c2a296d448ac52ffe45d194c to before ee5afb74688aa6f1f16d8c7e7b6bfaf803fb62fcAffected a319185be9f5ad13c2a296d448ac52ffe45d194c to before b28b862b07257219755d0b0a7fbe5d23b7c9ea91Affected a319185be9f5ad13c2a296d448ac52ffe45d194c to before 3d595affbe00a2e8bf43b9f2947a8efcdc1c059eAffected a319185be9f5ad13c2a296d448ac52ffe45d194c to before 6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6Affected a319185be9f5ad13c2a296d448ac52ffe45d194c to before fd2bd9fa7700ddf28296486b2598cff2f80cc819Affected a319185be9f5ad13c2a296d448ac52ffe45d194c to before 8817005efbdfdf5d4e4814cb5dc52b53d12917d7Affected
LinuxLinux	6.1Affected before 6.1Not affected 6.1.191 through 6.1.Not affected 6.6.160 through 6.6.Not affected 6.12.114 through 6.12.Not affected 6.18.34 through 6.18.Not affected 7.0.11 through 7.0.*Not affected 7.1 and laterNot affected

Product

Versions

LinuxLinux

a319185be9f5ad13c2a296d448ac52ffe45d194c to before ee5afb74688aa6f1f16d8c7e7b6bfaf803fb62fcAffected
a319185be9f5ad13c2a296d448ac52ffe45d194c to before b28b862b07257219755d0b0a7fbe5d23b7c9ea91Affected
a319185be9f5ad13c2a296d448ac52ffe45d194c to before 3d595affbe00a2e8bf43b9f2947a8efcdc1c059eAffected
a319185be9f5ad13c2a296d448ac52ffe45d194c to before 6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6Affected
a319185be9f5ad13c2a296d448ac52ffe45d194c to before fd2bd9fa7700ddf28296486b2598cff2f80cc819Affected
a319185be9f5ad13c2a296d448ac52ffe45d194c to before 8817005efbdfdf5d4e4814cb5dc52b53d12917d7Affected

LinuxLinux

6.1Affected
before 6.1Not affected
6.1.191 through 6.1.*Not affected
6.6.160 through 6.6.*Not affected
6.12.114 through 6.12.*Not affected
6.18.34 through 6.18.*Not affected
7.0.11 through 7.0.*Not affected
7.1 and laterNot affected

References

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