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bpf: Reject registration of duplicated kfunc

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Search for duplicated kfunc in btf_vmlinux and btf_modules
before a kernel module attempts to register a kfunc.
If kfunc would shadow existing kfunc then pr_err() and
reject module loading.

Reviewed-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Song Chen <chensong_2000@126.com>
Link: https://lore.kernel.org/r/20260603091910.7212-1-chensong_2000@126.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Song Chen 2026-06-03 17:19:10 +08:00 committed by Alexei Starovoitov
parent 390dc36ccf
commit 27ffbfd14d
1 changed files with 35 additions and 1 deletions
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36
kernel/bpf/btf.c
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@ -8771,6 +8771,39 @@ static int btf_check_iter_kfuncs(struct btf *btf, const char *func_name,
return 0;
}
static int btf_check_kfunc_name(struct btf *btf, const char *func_name, u32 kind)
{
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module *btf_mod, *tmp;
#endif
s32 id;
if (!btf_is_module(btf))
return 0;
id = btf_find_by_name_kind(bpf_get_btf_vmlinux(), func_name, kind);
if (id >= 0) {
pr_err("kfunc %s (id: %d) is already present in vmlinux.\n",
func_name, id);
return -EINVAL;
}
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
guard(mutex)(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->btf == btf)
continue;
id = btf_find_by_name_kind(btf_mod->btf, func_name, kind);
if (id >= 0) {
pr_err("kfunc %s (id: %d) is already present in module %s.\n",
func_name, id, btf_mod->module->name);
return -EINVAL;
}
}
#endif
return 0;
}
static int btf_check_kfunc_protos(struct btf *btf, u32 func_id, u32 func_flags)
{
const struct btf_type *func;
@ -8784,7 +8817,8 @@ static int btf_check_kfunc_protos(struct btf *btf, u32 func_id, u32 func_flags)
/* sanity check kfunc name */
func_name = btf_name_by_offset(btf, func->name_off);
if (!func_name || !func_name[0])
if (!func_name || !func_name[0] ||
btf_check_kfunc_name(btf, func_name, BTF_INFO_KIND(func->info)))
return -EINVAL;
func = btf_type_by_id(btf, func->type);