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.
Affected products
linux: linux kernel
References6
- git.kernel.org/stable/c/6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6 Patch
- git.kernel.org/stable/c/8817005efbdfdf5d4e4814cb5dc52b53d12917d7 Patch
- git.kernel.org/stable/c/fd2bd9fa7700ddf28296486b2598cff2f80cc819 Patch
- git.kernel.org/stable/c/3d595affbe00a2e8bf43b9f2947a8efcdc1c059e
- git.kernel.org/stable/c/b28b862b07257219755d0b0a7fbe5d23b7c9ea91
- git.kernel.org/stable/c/ee5afb74688aa6f1f16d8c7e7b6bfaf803fb62fc
Metrics
- CVSS 3.1
-
7.8
HIGH
Score source: CNA
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 3 · as of 14 November 2026
- CWE
- CWE-129CWE-125
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