CVE-2026-98813 (GCVE-0-2026-98813)
Vulnerability from cvelistv5
Published
2026-10-18 15:48
Modified
2026-10-19 09:26
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
bpf: Hold map BTF for the memory allocator destructor record
bpf_ma_set_dtor() duplicates map->record so that the bpf_mem_alloc
destructor can release the special fields of hash and rhash map elements
once the allocator frees them for good. btf_record_dup() only acquires
references on kernel and module BTF. Fields whose types live in the map
BTF keep pointing into it: a kptr to a local type refers to map->btf,
and a list_head or rb_root field carries a value_rec owned by the struct
meta table of map->btf.
That borrowed state can outlive the map. When RCU callbacks are still in
flight, bpf_mem_alloc_destroy() copies the allocator and defers the final
drain, together with the destructor context, to a workqueue.
bpf_map_free() then frees map->record and drops the map's BTF reference
as soon as map_free() returns. Once the program that loaded the BTF is
gone as well, the BTF is freed while the worker still uses the
duplicate. The worker dereferences it through btf_is_kernel() and
btf_find_struct_meta() in bpf_obj_free_fields() when destroying elements
that were freed under RCU, and through btf_is_kernel() in
btf_record_free() when releasing the context itself:
BUG: KASAN: slab-use-after-free in btf_is_kernel+0x19/0x30
Read of size 1 at addr ffff88811505dce8 by task kworker/u16:2/50
Workqueue: events_unbound free_mem_alloc_deferred
Call Trace:
btf_is_kernel+0x19/0x30
btf_record_free+0xc7/0xf0
htab_dtor_ctx_free+0x1a/0x30
free_mem_alloc_no_barrier+0x39/0x230
free_mem_alloc_deferred+0x2a/0x40
process_scheduled_works+0x5ce/0x9d0
worker_thread+0x42a/0x5e0
kthread+0x1f5/0x230
ret_from_fork+0x1dd/0x390
ret_from_fork_asm+0x1a/0x30
Allocated by task 358:
__kmalloc_cache_noprof+0x287/0x510
btf_new_fd+0xf7/0x3d0
__sys_bpf+0x487/0x840
Freed by task 0:
kfree+0x186/0x560
rcu_core+0x6f6/0xd40
Freeing a map that still holds more elements than the allocator's high
watermark is enough to get there, because the bulk free during teardown
queues the RCU callback that makes bpf_mem_alloc_destroy() defer.
Non-preallocated hash maps and resizable hash maps both register the
destructor and are affected alike.
Keep one reference on the map BTF in the destructor context. Every
non-kernel pointer in the duplicated record is either map->btf or memory
owned by it, so a single reference covers kptrs, list heads, and rb
roots, and mirrors what bpf_map_meta_alloc() does for the duplicated
record of an inner map. Release it only after the duplicated record has
been freed: the worker is preemptible and not in an RCU read-side
critical section, so dropping the last reference first would let the
BTF be freed while btf_record_free() still reads its fields.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"kernel/bpf/hashtab.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "b506f5699e145196ee29d76cf1ca1cbb2202c055",
"status": "affected",
"version": "1df97a7453eec80c1912c2d0360290a3970a7671",
"versionType": "git"
},
{
"lessThan": "ab39974240a0cff765f3bb9cce81d8001ffdb144",
"status": "affected",
"version": "1df97a7453eec80c1912c2d0360290a3970a7671",
"versionType": "git"
},
{
"status": "affected",
"version": "451a84a3ad3c897c03181af433e7c98640730f1f",
"versionType": "git"
},
{
"status": "affected",
"version": "51a17f0ce19c4ee2a25cf16c93490d509b1ebb0a",
"versionType": "git"
},
{
"lessThan": "6.13",
"status": "affected",
"version": "6.12.112",
"versionType": "semver"
},
{
"lessThan": "6.19",
"status": "affected",
"version": "6.18.55",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"kernel/bpf/hashtab.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "7.0"
},
{
"lessThan": "7.0",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.10",
"versionStartIncluding": "7.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "7.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.12.112",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.18.55",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Hold map BTF for the memory allocator destructor record\n\nbpf_ma_set_dtor() duplicates map-\u003erecord so that the bpf_mem_alloc\ndestructor can release the special fields of hash and rhash map elements\nonce the allocator frees them for good. btf_record_dup() only acquires\nreferences on kernel and module BTF. Fields whose types live in the map\nBTF keep pointing into it: a kptr to a local type refers to map-\u003ebtf,\nand a list_head or rb_root field carries a value_rec owned by the struct\nmeta table of map-\u003ebtf.\n\nThat borrowed state can outlive the map. When RCU callbacks are still in\nflight, bpf_mem_alloc_destroy() copies the allocator and defers the final\ndrain, together with the destructor context, to a workqueue.\nbpf_map_free() then frees map-\u003erecord and drops the map\u0027s BTF reference\nas soon as map_free() returns. Once the program that loaded the BTF is\ngone as well, the BTF is freed while the worker still uses the\nduplicate. The worker dereferences it through btf_is_kernel() and\nbtf_find_struct_meta() in bpf_obj_free_fields() when destroying elements\nthat were freed under RCU, and through btf_is_kernel() in\nbtf_record_free() when releasing the context itself:\n\n BUG: KASAN: slab-use-after-free in btf_is_kernel+0x19/0x30\n Read of size 1 at addr ffff88811505dce8 by task kworker/u16:2/50\n Workqueue: events_unbound free_mem_alloc_deferred\n Call Trace:\n btf_is_kernel+0x19/0x30\n btf_record_free+0xc7/0xf0\n htab_dtor_ctx_free+0x1a/0x30\n free_mem_alloc_no_barrier+0x39/0x230\n free_mem_alloc_deferred+0x2a/0x40\n process_scheduled_works+0x5ce/0x9d0\n worker_thread+0x42a/0x5e0\n kthread+0x1f5/0x230\n ret_from_fork+0x1dd/0x390\n ret_from_fork_asm+0x1a/0x30\n\n Allocated by task 358:\n __kmalloc_cache_noprof+0x287/0x510\n btf_new_fd+0xf7/0x3d0\n __sys_bpf+0x487/0x840\n\n Freed by task 0:\n kfree+0x186/0x560\n rcu_core+0x6f6/0xd40\n\nFreeing a map that still holds more elements than the allocator\u0027s high\nwatermark is enough to get there, because the bulk free during teardown\nqueues the RCU callback that makes bpf_mem_alloc_destroy() defer.\nNon-preallocated hash maps and resizable hash maps both register the\ndestructor and are affected alike.\n\nKeep one reference on the map BTF in the destructor context. Every\nnon-kernel pointer in the duplicated record is either map-\u003ebtf or memory\nowned by it, so a single reference covers kptrs, list heads, and rb\nroots, and mirrors what bpf_map_meta_alloc() does for the duplicated\nrecord of an inner map. Release it only after the duplicated record has\nbeen freed: the worker is preemptible and not in an RCU read-side\ncritical section, so dropping the last reference first would let the\nBTF be freed while btf_record_free() still reads its fields."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-19T09:26:06.490Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/b506f5699e145196ee29d76cf1ca1cbb2202c055"
},
{
"url": "https://git.kernel.org/stable/c/ab39974240a0cff765f3bb9cce81d8001ffdb144"
}
],
"title": "bpf: Hold map BTF for the memory allocator destructor record",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-98813",
"datePublished": "2026-10-18T15:48:59.745Z",
"dateReserved": "2026-09-25T10:25:14.371Z",
"dateUpdated": "2026-10-19T09:26:06.490Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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