linux-kernel - [PATCH] bpf: Fix holes in special_kfunc_list if !CONFIG

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Message-Id: <20241219-bpf-fix-special_kfunc_list-v1-1-d9d50dd61505@weissschuh.net>
Date: Thu, 19 Dec 2024 22:41:41 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, 
 John Fastabend <john.fastabend@...il.com>, 
 Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>, 
 Alexei Starovoitov <ast@...nel.org>
Subject: [PATCH] bpf: Fix holes in special_kfunc_list if !CONFIG_NET

If the function is not available its entry has to be replaced with
BTF_ID_UNUSED instead of skipped.
Otherwise the list doesn't work correctly.

Reported-by: Alexei Starovoitov <alexei.starovoitov@...il.com>
Closes: https://lore.kernel.org/lkml/CAADnVQJQpVziHzrPCCpGE5=8uzw2OkxP8gqe1FkJ6_XVVyVbNw@mail.gmail.com/
Fixes: 00a5acdbf398 ("bpf: Fix configuration-dependent BTF function references")
Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 kernel/bpf/verifier.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f27274e933e55342dcefa482a9ac75313d0d3469..44616b492f87cf4e1dc354e34d9158f13079dda7 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11739,6 +11739,9 @@ BTF_ID(func, bpf_rbtree_first)
 #ifdef CONFIG_NET
 BTF_ID(func, bpf_dynptr_from_skb)
 BTF_ID(func, bpf_dynptr_from_xdp)
+#else
+BTF_ID_UNUSED
+BTF_ID_UNUSED
 #endif
 BTF_ID(func, bpf_dynptr_slice)
 BTF_ID(func, bpf_dynptr_slice_rdwr)

---
base-commit: c2ce3bb13ae7f4445a5e8fb12254b2dacefd309c
change-id: 20241219-bpf-fix-special_kfunc_list-cddcf0ba5216

Best regards,
-- 
Thomas Weißschuh <linux@...ssschuh.net>