{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-98813", "modified": "2026-11-06T05:30:01Z", "upstream": [ "CVE-2026-98813" ], "published": "2026-10-18T15:54:51Z", "summary": "bpf: Hold map BTF for the memory allocator destructor record", "details": "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.", "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.12.115-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.12.115+rpt-rpi-2712", "binary_version": "1:6.12.115-1+rpt1" }, { "binary_name": "linux-image-6.12.115+rpt-rpi-v6", "binary_version": "1:6.12.115-1+rpt1" }, { "binary_name": "linux-image-6.12.115+rpt-rpi-v7", "binary_version": "1:6.12.115-1+rpt1" }, { "binary_name": "linux-image-6.12.115+rpt-rpi-v7l", "binary_version": "1:6.12.115-1+rpt1" }, { "binary_name": "linux-image-6.12.115+rpt-rpi-v8", "binary_version": "1:6.12.115-1+rpt1" }, { "binary_name": "linux-image-6.12.115+rpt-rpi-v8-rt", "binary_version": "1:6.12.115-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.12.115-1+rpt1": { "linux_commit": "2569533d6c33c15231fbc21704c87fcebc67173c", "upstream_version": "6.12.115", "assessment": "commit ancestry (strak rule)", "upstream_fixed": null } } } }, { "package": { "ecosystem": "Raspberry Pi OS:13", "name": "linux" }, "versions": [ "1:6.18.60-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.18.60+rpt-rpi-2712", "binary_version": "1:6.18.60-1+rpt1" }, { "binary_name": "linux-image-6.18.60+rpt-rpi-v6", "binary_version": "1:6.18.60-1+rpt1" }, { "binary_name": "linux-image-6.18.60+rpt-rpi-v7", "binary_version": "1:6.18.60-1+rpt1" }, { "binary_name": "linux-image-6.18.60+rpt-rpi-v8", "binary_version": "1:6.18.60-1+rpt1" }, { "binary_name": "linux-image-6.18.60+rpt-rpi-v8-rt", "binary_version": "1:6.18.60-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.18.60-1+rpt1": { "linux_commit": "0b41724521c9adf5399409d02aece6c1df0a4432", "upstream_version": "6.18.60", "assessment": "commit ancestry (strak rule)", "upstream_fixed": null } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-98813" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/b506f5699e145196ee29d76cf1ca1cbb2202c055" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/ab39974240a0cff765f3bb9cce81d8001ffdb144" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-10-19T09:36:19Z" } }