bpf: Make reg_not_null() true for CONST_PTR_TO_MAP

[ Upstream commit 5534e58f ]

When reg->type is CONST_PTR_TO_MAP, it can not be null. However the
verifier explores the branches under rX == 0 in check_cond_jmp_op()
even if reg->type is CONST_PTR_TO_MAP, because it was not checked for
in reg_not_null().

Fix this by adding CONST_PTR_TO_MAP to the set of types that are
considered non nullable in reg_not_null().

An old "unpriv: cmp map pointer with zero" selftest fails with this
change, because now early out correctly triggers in
check_cond_jmp_op(), making the verification to pass.

In practice verifier may allow pointer to null comparison in unpriv,
since in many cases the relevant branch and comparison op are removed
as dead code. So change the expected test result to __success_unpriv.

Signed-off-by: Ihor Solodrai <isolodrai@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250609183024.359974-2-isolodrai@meta.com


Signed-off-by: Sasha Levin <sashal@kernel.org>