bpf: Reject key-less BTF for hash maps
Summary
| CVE | CVE-2026-98065 |
|---|
| State | PUBLISHED |
|---|
| Assigner | Linux |
|---|
| Source Priority | CVE Program / NVD first with legacy fallback |
|---|
| Published | 2026-09-25 11:17:35 UTC |
|---|
| Updated | 2026-09-25 11:17:35 UTC |
|---|
| Description | In the Linux kernel, the following vulnerability has been resolved:
bpf: Reject key-less BTF for hash maps
map_check_btf() allows a key-less BTF (btf_key_type_id == 0) only for
maps that have a ->map_check_btf callback, and leaves the actual
decision to that callback. Hash maps used to have no ->map_check_btf,
so a key-less BTF was rejected outright.
That changed when htab and rhtab gained a ->map_check_btf to register a
dtor - htab in commit 1df97a7453ee ("bpf: Register dtor for freeing
special fields") and rhtab in commit 6905f8601298 ("bpf: Allow special
fields in resizable hashtab"). Neither looks at the key, so a key-less
hash map now passes map_check_btf() and gets created. Reading it back
through bpffs feeds the key type_id 0 into btf_type_seq_show();
btf_type_by_id() returns the void type, kind_ops[BTF_KIND_UNKN] is NULL,
and btf_type_show() dereferences it:
RIP: 0010:btf_type_show+0x223/0x2e0 kernel/bpf/btf.c:8232
RSP: 0018:ffffc9000399f868 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000028
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: ffffc9000399f970 R11: 0000000000000001 R12: ffffffff9b96b140
R13: ffffc9000399f8e0 R14: ffff88803d393c00 R15: 0000000000000003
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 000000003d213000 CR4: 0000000000352ef0
DR0: 0000000039ae8f55 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
btf_type_seq_show_flags+0xca/0x120 kernel/bpf/btf.c:8250
htab_map_seq_show_elem+0x12e/0x350 kernel/bpf/hashtab.c:1669
map_seq_show+0x13d/0x1e0 kernel/bpf/inode.c:293
traverse.part.0.constprop.0+0x107/0x650 fs/seq_file.c:112
traverse fs/seq_file.c:99 [inline]
seq_read_iter+0x93f/0x1270 fs/seq_file.c:196
seq_read+0x344/0x4d0 fs/seq_file.c:163
vfs_read+0x1e4/0xb40 fs/read_write.c:572
ksys_pread64 fs/read_write.c:764 [inline]
__do_sys_pread64 fs/read_write.c:772 [inline]
__se_sys_pread64 fs/read_write.c:769 [inline]
__x64_sys_pread64+0x1eb/0x250 fs/read_write.c:769
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Reject a key-less BTF in htab_map_check_btf() and rhtab_map_check_btf(),
restoring the previous behavior. |
|---|
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 1df97a7453eec80c1912c2d0360290a3970a7671 7ca231252820c47aaec42a5db580db98f9b64724 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1df97a7453eec80c1912c2d0360290a3970a7671 0895a0c0734703be5532f3883c42db95615fd98b git |
Not specified |
| CNA |
Linux |
Linux |
affected 7.0 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.0 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.7 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3-rc2 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/0895a0c0734703be5532f3883c42db95615fd98b |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/7ca231252820c47aaec42a5db580db98f9b64724 |
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.