{"id":"CVE-2026-98813","revision":"9f725c34739e4d05bde81c3e98e32752","records":[{"revision":"9f725c34739e4d05bde81c3e98e32752","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98813","aliases":[],"title":"bpf: Hold map BTF for the memory allocator destructor record","description":"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->record 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->btf,\nand a list_head or rb_root field carries a value_rec owned by the struct\nmeta table of map->btf.\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->record and drops the map's 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's 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->btf 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.","state":0,"publishedAt":"2026-10-18T15:48:59.745+00:00","modifiedAt":"2026-10-19T09:26:06.49+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/hashtab.c\"\n ],\n \"versions\": [\n {\n \"version\": \"1df97a7453eec80c1912c2d0360290a3970a7671\",\n \"lessThan\": \"b506f5699e145196ee29d76cf1ca1cbb2202c055\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"1df97a7453eec80c1912c2d0360290a3970a7671\",\n \"lessThan\": \"ab39974240a0cff765f3bb9cce81d8001ffdb144\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"451a84a3ad3c897c03181af433e7c98640730f1f\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"51a17f0ce19c4ee2a25cf16c93490d509b1ebb0a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6.12.112\",\n \"lessThan\": \"6.13\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.55\",\n \"lessThan\": \"6.19\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\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/hashtab.c\"\n ],\n \"versions\": [\n {\n \"version\": \"7.0\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"7.0\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2.10\",\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":[],"references":["https://git.kernel.org/stable/c/b506f5699e145196ee29d76cf1ca1cbb2202c055","https://git.kernel.org/stable/c/ab39974240a0cff765f3bb9cce81d8001ffdb144"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98813","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98813","identifiers":["CVE-2026-98813"]},"retained":false,"historicalAffected":[]}],"coverage":[]}