CVE-2024-49861
- Source
- https://cve.org/CVERecord?id=CVE-2024-49861
- Import Source
- https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-49861.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/CVE-2024-49861
- Downstream
- Related
- Published
- 2024-10-21T12:27:19Z
- Modified
- 2026-08-12T03:30:12Z
- Severity
-
- 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
- Summary
- bpf: Fix helper writes to read-only maps
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix helper writes to read-only maps
Lonial found an issue that despite user- and BPF-side frozen BPF map (like in case of .rodata), it was still possible to write into it from a BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT} as arguments.
In check_func_arg() when the argument is as mentioned, the meta->raw_mode is never set. Later, check_helper_mem_access(), under the case of PTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the subsequent call to check_map_access_type() and given the BPF map is read-only it succeeds.
The helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT when results are written into them as opposed to read out of them. The latter indicates that it's okay to pass a pointer to uninitialized memory as the memory is written to anyway.
However, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM just with additional alignment requirement. So it is better to just get rid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the fixed size memory types. For this, add MEM_ALIGNED to additionally ensure alignment given these helpers write directly into the args via = val. The .arg_size has been initialized reflecting the actual sizeof(*).
MEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated argument types, since in !MEM_FIXED_SIZE cases the verifier does not know the buffer size a priori and therefore cannot blindly write * = val.
- Database specific
{ "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/49xxx/CVE-2024-49861.json" }- References
-
- https://git.kernel.org/stable/c/1e75d25133158b525e0456876e9bcfd6b2993fd5
- https://git.kernel.org/stable/c/2ed98ee02d1e08afee88f54baec39ea78dc8a23c
- https://git.kernel.org/stable/c/32556ce93bc45c730829083cb60f95a2728ea48b
- https://git.kernel.org/stable/c/988e55abcf7fdb8fc9a76a7cf3f4e939a4d4fb3a
- https://git.kernel.org/stable/c/a2c8dc7e21803257e762b0bf067fd13e9c995da0
- https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/49xxx/CVE-2024-49861.json
- https://nvd.nist.gov/vuln/detail/CVE-2024-49861
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced57c3bb725a3dd97d960d7e1cd0845d88de53217fFixed988e55abcf7fdb8fc9a76a7cf3f4e939a4d4fb3aFixeda2c8dc7e21803257e762b0bf067fd13e9c995da0Fixed2ed98ee02d1e08afee88f54baec39ea78dc8a23cFixed1e75d25133158b525e0456876e9bcfd6b2993fd5Fixed32556ce93bc45c730829083cb60f95a2728ea48b