[PATCH bpf] bpf: Cleanup ftrace hash in bpf_trampoline_put

[PATCH bpf] bpf: Cleanup ftrace hash in bpf_trampoline_put

[Jiri Olsa]

We need to release possible hash from trampoline fops object
before removing it, otherwise we leak it.

Fixes: 00963a2e75a8 ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/trampoline.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 0f532e6a717f..ff87e38af8a7 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -841,7 +841,10 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
 	 * multiple rcu callbacks.
 	 */
 	hlist_del(&tr->hlist);
-	kfree(tr->fops);
+	if (tr->fops) {
+		ftrace_free_filter(tr->fops);
+		kfree(tr->fops);
+	}
 	kfree(tr);
 out:
 	mutex_unlock(&trampoline_mutex);
-- 
2.37.1

Re: [PATCH bpf] bpf: Cleanup ftrace hash in bpf_trampoline_put

[Song Liu]

On Tue, Aug 2, 2022 at 6:57 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> We need to release possible hash from trampoline fops object
> before removing it, otherwise we leak it.
>
> Fixes: 00963a2e75a8 ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Great catch! Thanks!

Acked-by: Song Liu <song@kernel.org>

> ---
>  kernel/bpf/trampoline.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
> index 0f532e6a717f..ff87e38af8a7 100644
> --- a/kernel/bpf/trampoline.c
> +++ b/kernel/bpf/trampoline.c
> @@ -841,7 +841,10 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
>          * multiple rcu callbacks.
>          */
>         hlist_del(&tr->hlist);
> -       kfree(tr->fops);
> +       if (tr->fops) {
> +               ftrace_free_filter(tr->fops);
> +               kfree(tr->fops);
> +       }
>         kfree(tr);
>  out:
>         mutex_unlock(&trampoline_mutex);
> --
> 2.37.1
>

Re: [PATCH bpf] bpf: Cleanup ftrace hash in bpf_trampoline_put

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Tue,  2 Aug 2022 15:56:51 +0200 you wrote:
> We need to release possible hash from trampoline fops object
> before removing it, otherwise we leak it.
> 
> Fixes: 00963a2e75a8 ("bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch)")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  kernel/bpf/trampoline.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

Here is the summary with links:
  - [bpf] bpf: Cleanup ftrace hash in bpf_trampoline_put
    https://git.kernel.org/bpf/bpf/c/62d468e5e100

You are awesome, thank you!
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