bpf: Add missing btf_put to register_btf_id_dtor_kfuncs

[ Upstream commit 74bc3a5acc82f020d2e126f56c535d02d1e74e37 ]

We take the BTF reference before we register dtors and we need
to put it back when it's done.

We probably won't se a problem with kernel BTF, but module BTF
would stay loaded (because of the extra ref) even when its module
is removed.

Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Fixes: 5ce937d613a4 ("bpf: Populate pairs of btf_id and destructor kfunc in btf")
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230120122148.1522359-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index efdbba2..a7c2f0c 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7607,9 +7607,9 @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
 
        sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL);
 
-       return 0;
 end:
-       btf_free_dtor_kfunc_tab(btf);
+       if (ret)
+               btf_free_dtor_kfunc_tab(btf);
        btf_put(btf);
        return ret;
 }