CVE-2026-98064

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix NULL-ptr-deref when showing a void BTF type

btf modifier show() resolves the modifier and then calls btf type ops(t)->show() unconditionally. For the void type (type id 0, BTF KIND UNKN) kind ops[] has no entry, so ->show is NULL.

A "const void" (a modifier resolving to void) cannot be a map key or value - map check btf() rejects it because void has no size - so the map dump path does not reach it. But bpf snprintf btf() takes a type id straight from the BPF program, and passing such a "const void" from the vmlinux BTF NULL-derefs:

KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] RIP: 0010:btf modifier show (kernel/bpf/btf.c:2914) Call Trace: btf type show (kernel/bpf/btf.c:8251) btf type snprintf show (kernel/bpf/btf.c:8321) bpf snprintf btf (kernel/trace/bpf trace.c:1047) bpf prog test run raw tp (net/bpf/test run.c:829) sys bpf (kernel/bpf/syscall.c:4804) do syscall 64 (arch/x86/entry/syscall 64.c:94) entry SYSCALL 64 after hwframe (arch/x86/entry/entry 64.S:121)

Fall back to btf df show() when the resolved type has no show op; it emits the "" placeholder already used for kinds like FWD and FUNC. bpf snprintf btf() then returns the length as usual.