ghsa-x96j-4m6x-jcvx
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix oob access in cgroup local storage
Lonial reported that an out-of-bounds access in cgroup local storage can be crafted via tail calls. Given two programs each utilizing a cgroup local storage with a different value size, and one program doing a tail call into the other. The verifier will validate each of the indivial programs just fine. However, in the runtime context the bpf_cg_run_ctx holds an bpf_prog_array_item which contains the BPF program as well as any cgroup local storage flavor the program uses. Helpers such as bpf_get_local_storage() pick this up from the runtime context:
ctx = container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx); storage = ctx->prog_item->cgroup_storage[stype];
if (stype == BPF_CGROUP_STORAGE_SHARED) ptr = &READ_ONCE(storage->buf)->data[0]; else ptr = this_cpu_ptr(storage->percpu_buf);
For the second program which was called from the originally attached one, this means bpf_get_local_storage() will pick up the former program's map, not its own. With mismatching sizes, this can result in an unintended out-of-bounds access.
To fix this issue, we need to extend bpf_map_owner with an array of storage_cookie[] to match on i) the exact maps from the original program if the second program was using bpf_get_local_storage(), or ii) allow the tail call combination if the second program was not using any of the cgroup local storage maps.
{
"affected": [],
"aliases": [
"CVE-2025-38502"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-08-16T10:15:25Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix oob access in cgroup local storage\n\nLonial reported that an out-of-bounds access in cgroup local storage\ncan be crafted via tail calls. Given two programs each utilizing a\ncgroup local storage with a different value size, and one program\ndoing a tail call into the other. The verifier will validate each of\nthe indivial programs just fine. However, in the runtime context\nthe bpf_cg_run_ctx holds an bpf_prog_array_item which contains the\nBPF program as well as any cgroup local storage flavor the program\nuses. Helpers such as bpf_get_local_storage() pick this up from the\nruntime context:\n\n ctx = container_of(current-\u003ebpf_ctx, struct bpf_cg_run_ctx, run_ctx);\n storage = ctx-\u003eprog_item-\u003ecgroup_storage[stype];\n\n if (stype == BPF_CGROUP_STORAGE_SHARED)\n ptr = \u0026READ_ONCE(storage-\u003ebuf)-\u003edata[0];\n else\n ptr = this_cpu_ptr(storage-\u003epercpu_buf);\n\nFor the second program which was called from the originally attached\none, this means bpf_get_local_storage() will pick up the former\nprogram\u0027s map, not its own. With mismatching sizes, this can result\nin an unintended out-of-bounds access.\n\nTo fix this issue, we need to extend bpf_map_owner with an array of\nstorage_cookie[] to match on i) the exact maps from the original\nprogram if the second program was using bpf_get_local_storage(), or\nii) allow the tail call combination if the second program was not\nusing any of the cgroup local storage maps.",
"id": "GHSA-x96j-4m6x-jcvx",
"modified": "2025-08-16T12:30:32Z",
"published": "2025-08-16T12:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38502"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/19341d5c59e8c7e8528e40f8663e99d67810473c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/abad3d0bad72a52137e0c350c59542d75ae4f513"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.