bpf: Harden bloom filter sizing and indexing on 32-bit kernels
In the Linux kernel, the following vulnerability has been resolved: bpf: Harden bloom filter sizing and indexing on 32-bit kernels bloom_map_alloc() has two 32-bit-specific problems when the computed bitmap reaches the U32_MAX fallback case. First, BITS_TO_BYTES(U32_MAX) is evaluated with 32-bit arithmetic. The addition performed by DIV_ROUND_UP wraps, so the map allocates only the fixed-size bloom filter object while keeping bitset_mask == U32_MAX. Subsequent updates can then write past the allocated object. Second, fixing only the allocation size is not sufficient. The bloom hash is a u32, but set_bit() takes a signed long bit number and x86 test_bit() eventually feeds the index to variable_test_bit(long, ...). On 32-bit kernels, hashes in [0x80000000, U32_MAX] therefore become negative bit offsets. x86 bt/bts with a memory operand interpret those offsets relative to the supplied base, so a map with bitset_mask == U32_MAX can read or write before bloom->bitset even after allocating the full 512 MiB bitmap. Keep the U32_MAX fallback, but split each hash into a word pointer and an in-word bit number before calling test_bit() or set_bit(). The bitops argument is then always in [0, BITS_PER_LONG - 1], while BIT_WORD(h) still selects the intended word in the full bitmap. Compute the bitset size from (u64)bitset_mask + 1 before passing the final size to bpf_map_area_alloc(). This fixes the original under-allocation and keeps the allocated storage consistent with the addressable b
CVE-2026-89579
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-89579
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "9330986c03006ab1d33d243b7cfe598a7a3c1baa",
"lessThan": "a6183bc683f97f4317f7e84939ca7fff37c5688b",
"versionType": "git"
},
{
"status": "affected",
"version": "9330986c03006ab1d33d243b7cfe598a7a3c1baa",
"lessThan": "80551bf8912c42d1e3d55eec6fa3c40f306c3de8",
"versionType": "git"
},
{
"status": "affected",
"version": "9330986c03006ab1d33d243b7cfe598a7a3c1baa",
"lessThan": "3b7a13eccfcf97714ffc1ca6aa663d66d4a30e29",
"versionType": "git"
},
{
"status": "affected",
"version": "9330986c03006ab1d33d243b7cfe598a7a3c1baa",
"lessThan": "272fcb4ba6fab678db0eb966dc81c4c804bef64a",
"versionType": "git"
},
{
"status": "affected",
"version": "9330986c03006ab1d33d243b7cfe598a7a3c1baa",
"lessThan": "dff481e12b3f127739f6a4ea7cef2c25dc12e056",
"versionType": "git"
},
{
"status": "affected",
"version": "9330986c03006ab1d33d243b7cfe598a7a3c1baa",
"lessThan": "11c1e836710dcba03e50454a4eedfdbaf8d3050e",
"versionType": "git"
}
],
"programFiles": [
"kernel/bpf/bloom_filter.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.16"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.16",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.109",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.50",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/bpf/bloom_filter.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89579
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #35088 · Revision 1
- Added to Heist Feed
- Publisher date