[PATCHv2 bpf] bpf: Add missing btf_put to register_btf_id_dtor_kfuncs

[PATCHv2 bpf] bpf: Add missing btf_put to register_btf_id_dtor_kfuncs

[Jiri Olsa]

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>
---
v2 changes:
  - resend and added Kumar's ack

 kernel/bpf/btf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index f7dd8af06413..b7017cae6fd1 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7782,9 +7782,9 @@ 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;
 }
-- 
2.39.0

Re: [PATCHv2 bpf] bpf: Add missing btf_put to register_btf_id_dtor_kfuncs

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Fri, 20 Jan 2023 13:21:48 +0100 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [PATCHv2,bpf] bpf: Add missing btf_put to register_btf_id_dtor_kfuncs
    https://git.kernel.org/bpf/bpf/c/74bc3a5acc82

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html