2022-10-25 08:41:45

by Chuang Wang

Subject: [PATCH] bpf: Clean up all resources when register_fprobe_ips returns an error

When register_fprobe_ips returns an error, bpf_link_cleanup just cleans
up bpf_link_primer's resources and forgets to clean up
bpf_kprobe_multi_link, addrs, cookies.

So, by adding 'goto error', this ensures that all resources are cleaned
up.

Cc: [email protected]
Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
Signed-off-by: Chuang Wang <[email protected]>
---
kernel/trace/bpf_trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 1ed08967fb97..5b806ef20857 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2778,7 +2778,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
err = register_fprobe_ips(&link->fp, addrs, cnt);
if (err) {
bpf_link_cleanup(&link_primer);
- return err;
+ goto error;
}

return bpf_link_settle(&link_primer);
--
2.34.1

2022-10-25 09:07:47

by Jiri Olsa

Subject: Re: [PATCH] bpf: Clean up all resources when register_fprobe_ips returns an error

On Tue, Oct 25, 2022 at 04:06:28PM +0800, Chuang Wang wrote:
> When register_fprobe_ips returns an error, bpf_link_cleanup just cleans
> up bpf_link_primer's resources and forgets to clean up
> bpf_kprobe_multi_link, addrs, cookies.
>
> So, by adding 'goto error', this ensures that all resources are cleaned
> up.
>
> Cc: [email protected]
> Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
> Signed-off-by: Chuang Wang <[email protected]>
> ---
> kernel/trace/bpf_trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 1ed08967fb97..5b806ef20857 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2778,7 +2778,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> err = register_fprobe_ips(&link->fp, addrs, cnt);
> if (err) {
> bpf_link_cleanup(&link_primer);
> - return err;
> + goto error;

that should be taken care of bpf_kprobe_multi_link_dealloc,
through the fput path in bpf_link_cleanup

do you see any related memory leak like report in kmemleak?

jirka

> }
>
> return bpf_link_settle(&link_primer);
> --
> 2.34.1
>

2022-10-25 09:40:31

by Chuang Wang

Subject: Re: [PATCH] bpf: Clean up all resources when register_fprobe_ips returns an error

Sorry, I didn't notice this.

On Tue, Oct 25, 2022 at 5:01 PM Jiri Olsa <[email protected]> wrote:
>
> On Tue, Oct 25, 2022 at 04:06:28PM +0800, Chuang Wang wrote:
> > When register_fprobe_ips returns an error, bpf_link_cleanup just cleans
> > up bpf_link_primer's resources and forgets to clean up
> > bpf_kprobe_multi_link, addrs, cookies.
> >
> > So, by adding 'goto error', this ensures that all resources are cleaned
> > up.
> >
> > Cc: [email protected]
> > Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
> > Signed-off-by: Chuang Wang <[email protected]>
> > ---
> > kernel/trace/bpf_trace.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index 1ed08967fb97..5b806ef20857 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -2778,7 +2778,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> > err = register_fprobe_ips(&link->fp, addrs, cnt);
> > if (err) {
> > bpf_link_cleanup(&link_primer);
> > - return err;
> > + goto error;
>
> that should be taken care of bpf_kprobe_multi_link_dealloc,
> through the fput path in bpf_link_cleanup
>
> do you see any related memory leak like report in kmemleak?
>
> jirka
>
> > }
> >
> > return bpf_link_settle(&link_primer);
> > --
> > 2.34.1
> >