From: Sami Tolvanen <samitolvanen@google.com>
Date: Sat, 10 Jan 2026 08:25:53 +0000 (+0000)
Subject: bpf, btf: Enforce destructor kfunc type with CFI
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=99fde4d0626176d03cea35c64a063df73816e64d;p=thirdparty%2Flinux.git

bpf, btf: Enforce destructor kfunc type with CFI

Ensure that registered destructor kfuncs have the same type
as btf_dtor_kfunc_t to avoid a kernel panic on systems with
CONFIG_CFI enabled.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260110082548.113748-10-samitolvanen@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 539c9fdea41d9..2c6076fc29b94 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8846,6 +8846,13 @@ static int btf_check_dtor_kfuncs(struct btf *btf, const struct btf_id_dtor_kfunc
 		 */
 		if (!t || !btf_type_is_ptr(t))
 			return -EINVAL;
+
+		if (IS_ENABLED(CONFIG_CFI_CLANG)) {
+			/* Ensure the destructor kfunc type matches btf_dtor_kfunc_t */
+			t = btf_type_by_id(btf, t->type);
+			if (!btf_type_is_void(t))
+				return -EINVAL;
+		}
 	}
 	return 0;
 }