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Sat, 19 Sep 2026 09:42:34 -0700 (PDT) Received: from localhost.localdomain ([2405:201:51:102d:5562:18f8:11da:acda]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33c3311a6e5sm7104245eec.7.2026.09.19.09.42.32 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sat, 19 Sep 2026 09:42:34 -0700 (PDT) From: Abhinav Madake To: bpf@vger.kernel.org Cc: Andrii Nakryiko , Eduard Zingerman , Ihor Solodrai , Abhinav Madake Subject: [PATCH bpf-next] libbpf: Return -EINVAL from btf__align_of() for unknown type ID Date: Sat, 19 Sep 2026 22:12:29 +0530 Message-ID: <20260919164229.95154-1-abhinavmadake@gmail.com> X-Mailer: git-send-email 2.47.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit btf__align_of() passes the result of btf__type_by_id() straight to btf_kind() without checking for NULL, so an unknown type ID dereferences a NULL pointer instead of returning an error like the other btf__*() lookups do. BTF parsed from raw data cannot trigger this, since btf_sanity_check() rejects dangling references. BTF built with the btf__add_*() API can: those only check the ID range, so a forward reference to a type that was never added, followed by btf__align_of() on it (directly, or through the recursive struct/array/typedef cases), crashes. Check for NULL and return -EINVAL, matching btf__type_by_id(). Link: https://github.com/libbpf/libbpf/issues/983 Signed-off-by: Abhinav Madake --- tools/lib/bpf/btf.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 908bd3442..d15bc09ac 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -986,8 +986,12 @@ done: int btf__align_of(const struct btf *btf, __u32 id) { const struct btf_type *t = btf__type_by_id(btf, id); - __u16 kind = btf_kind(t); + __u16 kind; + if (!t) + return libbpf_err(-EINVAL); + + kind = btf_kind(t); switch (kind) { case BTF_KIND_INT: case BTF_KIND_ENUM: -- 2.47.0