bpf: Tag nullable kfunc pointer args with PTR_MAYBE_NULL

Browse source

Now that get_kfunc_ptr_arg_type() classifies a kfunc pointer argument
from its BTF alone, express a nullable argument by OR-ing PTR_MAYBE_NULL
into the classified type, and resolve a NULL register after
classification instead of before it.

Previously check_kfunc_args() short-circuited a nullable argument passed
a NULL register with a continue placed before get_kfunc_ptr_arg_type(),
so the NULL never reached classification. That kept a register-state
decision (bpf_register_is_null()) ahead of the BTF-based classification.

This mirrors how helper arguments carry PTR_MAYBE_NULL in their
bpf_arg_type and is a step toward describing kfuncs with a bpf_func_proto:
the nullability now travels with the per-argument classification, so it is
captured when the prototype is generated at add-call time.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260801074633.1595644-17-ameryhung@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

...

This commit is contained in:

Amery Hung 2026-08-01 00:46:31 -07:00 • committed by Kumar Kartikeya Dwivedi

parent c9e995ba0d

commit ba5b99470c

No known key found for this signature in database

GPG key ID: 472D377B63542F83

1 changed files with 67 additions and 80 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

147

kernel/bpf/verifier.c

View file