{"id":"CVE-2026-89579","revision":"349ab0dea2bc427da1b0484aa247f6b0","records":[{"revision":"349ab0dea2bc427da1b0484aa247f6b0","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-89579","aliases":[],"title":"bpf: Harden bloom filter sizing and indexing on 32-bit kernels","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Harden bloom filter sizing and indexing on 32-bit kernels\n\nbloom_map_alloc() has two 32-bit-specific problems when the computed\nbitmap reaches the U32_MAX fallback case.\n\nFirst, BITS_TO_BYTES(U32_MAX) is evaluated with 32-bit arithmetic. The\naddition performed by DIV_ROUND_UP wraps, so the map allocates only the\nfixed-size bloom filter object while keeping bitset_mask == U32_MAX.\nSubsequent updates can then write past the allocated object.\n\nSecond, fixing only the allocation size is not sufficient. The bloom hash\nis a u32, but set_bit() takes a signed long bit number and x86 test_bit()\neventually feeds the index to variable_test_bit(long, ...). On 32-bit\nkernels, hashes in [0x80000000, U32_MAX] therefore become negative bit\noffsets. x86 bt/bts with a memory operand interpret those offsets relative\nto the supplied base, so a map with bitset_mask == U32_MAX can read or\nwrite before bloom->bitset even after allocating the full 512 MiB bitmap.\n\nKeep the U32_MAX fallback, but split each hash into a word pointer and an\nin-word bit number before calling test_bit() or set_bit(). The bitops\nargument is then always in [0, BITS_PER_LONG - 1], while BIT_WORD(h) still\nselects the intended word in the full bitmap.\n\nCompute the bitset size from (u64)bitset_mask + 1 before passing the final\nsize to bpf_map_area_alloc(). This fixes the original under-allocation and\nkeeps the allocated storage consistent with the addressable bitset.\n\nExploitation note: local privilege escalation is possible on a 32-bit x86\nkernel using the under-allocation bug from a binary with CAP_BPF.","state":0,"publishedAt":"2026-09-11T19:44:46.11+00:00","modifiedAt":"2026-10-19T08:49:12.203+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/bpf/bloom_filter.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\n                            \"lessThan\": \"a6183bc683f97f4317f7e84939ca7fff37c5688b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\n                            \"lessThan\": \"80551bf8912c42d1e3d55eec6fa3c40f306c3de8\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\n                            \"lessThan\": \"3b7a13eccfcf97714ffc1ca6aa663d66d4a30e29\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\n                            \"lessThan\": \"272fcb4ba6fab678db0eb966dc81c4c804bef64a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\n                            \"lessThan\": \"dff481e12b3f127739f6a4ea7cef2c25dc12e056\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9330986c03006ab1d33d243b7cfe598a7a3c1baa\",\n                            \"lessThan\": \"11c1e836710dcba03e50454a4eedfdbaf8d3050e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/bpf/bloom_filter.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"5.16\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"5.16\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.188\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.157\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.109\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.50\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.4\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/a6183bc683f97f4317f7e84939ca7fff37c5688b","https://git.kernel.org/stable/c/80551bf8912c42d1e3d55eec6fa3c40f306c3de8","https://git.kernel.org/stable/c/3b7a13eccfcf97714ffc1ca6aa663d66d4a30e29","https://git.kernel.org/stable/c/272fcb4ba6fab678db0eb966dc81c4c804bef64a","https://git.kernel.org/stable/c/dff481e12b3f127739f6a4ea7cef2c25dc12e056","https://git.kernel.org/stable/c/11c1e836710dcba03e50454a4eedfdbaf8d3050e"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89579","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-89579","identifiers":["CVE-2026-89579"]},"retained":false,"historicalAffected":[]}],"coverage":[]}