bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()
Summary
| CVE | CVE-2026-45839 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-27 11:16:23 UTC |
| Updated | 2026-05-27 14:48:03 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec() CO-RE accessor strings are colon-separated indices that describe a path from a root BTF type to a target field, e.g. "0:1:2" walks through nested struct members. bpf_core_parse_spec() parses each component with sscanf("%d"), so negative values like -1 are silently accepted. The subsequent bounds checks (access_idx >= btf_vlen(t)) only guard the upper bound and always pass for negative values because C integer promotion converts the __u16 btf_vlen result to int, making the comparison (int)(-1) >= (int)(N) false for any positive N. When -1 reaches btf_member_bit_offset() it gets cast to u32 0xffffffff, producing an out-of-bounds read far past the members array. A crafted BPF program with a negative CO-RE accessor on any struct that exists in vmlinux BTF (e.g. task_struct) crashes the kernel deterministically during BPF_PROG_LOAD on any system with CONFIG_DEBUG_INFO_BTF=y (default on major distributions). The bug is reachable with CAP_BPF: BUG: unable to handle page fault for address: ffffed11818b6626 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: Oops: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 85 Comm: poc Not tainted 7.0.0-rc6 #18 PREEMPT(full) RIP: 0010:bpf_core_parse_spec (tools/lib/bpf/relo_core.c:354) RAX: 00000000ffffffff Call Trace: <TASK> bpf_core_calc_relo_insn (tools/lib/bpf/relo_core.c:1321) bpf_core_apply (kernel/bpf/btf.c:9507) check_core_relo (kernel/bpf/verifier.c:19475) bpf_check (kernel/bpf/verifier.c:26031) bpf_prog_load (kernel/bpf/syscall.c:3089) __sys_bpf (kernel/bpf/syscall.c:6228) </TASK> CO-RE accessor indices are inherently non-negative (struct member index, array element index, or enumerator index), so reject them immediately after parsing. |
Risk And Classification
EPSS: 0.000150000 probability, percentile 0.035310000 (date 2026-05-27)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected ddc7c3042614e273044f698d2beab25cc3842d45 3ff85ae79e1a74baeb916b78a63d821f6d19a994 git | Not specified |
| CNA | Linux | Linux | affected ddc7c3042614e273044f698d2beab25cc3842d45 36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a git | Not specified |
| CNA | Linux | Linux | affected ddc7c3042614e273044f698d2beab25cc3842d45 76f2ebaf79a9ae6d0737b87f045fe769e425d78f git | Not specified |
| CNA | Linux | Linux | affected ddc7c3042614e273044f698d2beab25cc3842d45 99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2 git | Not specified |
| CNA | Linux | Linux | affected ddc7c3042614e273044f698d2beab25cc3842d45 1c22483a2c4bbf747787f328392ca3e68619c4dc git | Not specified |
| CNA | Linux | Linux | affected 5.4 | Not specified |
| CNA | Linux | Linux | unaffected 5.4 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.141 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.91 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.33 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0.10 7.0.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1-rc1 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/3ff85ae79e1a74baeb916b78a63d821f6d19a994 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/76f2ebaf79a9ae6d0737b87f045fe769e425d78f | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/1c22483a2c4bbf747787f328392ca3e68619c4dc | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.