netdev - Re: [PATCH] bpf: add missing percpu_counter_destroy() in htab_map

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Date:   Sat, 10 Sep 2022 13:16:56 -0700
From:   sdf@...gle.com
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Kumar Kartikeya Dwivedi <memxor@...il.com>,
        syzbot <syzbot+5d1da78b375c3b5e6c2b@...kaller.appspotmail.com>,
        syzkaller-bugs@...glegroups.com, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH] bpf: add missing percpu_counter_destroy() in htab_map_alloc()

On 09/11, Tetsuo Handa wrote:
> syzbot is reporting ODEBUG bug in htab_map_alloc() [1], for
> commit 86fe28f7692d96d2 ("bpf: Optimize element count in non-preallocated
> hash map.") added percpu_counter_init() to htab_map_alloc() but forgot to
> add percpu_counter_destroy() to the error path.

> Link: https://syzkaller.appspot.com/bug?extid=5d1da78b375c3b5e6c2b [1]
> Reported-by: syzbot  
> <syzbot+5d1da78b375c3b5e6c2b@...kaller.appspotmail.com>
> Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>

Thanks!

Reviewed-by: Stanislav Fomichev <sdf@...gle.com>

> Fixes: 86fe28f7692d96d2 ("bpf: Optimize element count in non-preallocated  
> hash map.")
> ---
>   kernel/bpf/hashtab.c | 2 ++
>   1 file changed, 2 insertions(+)

> diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
> index 0fe3f136cbbe..86aec20c22d0 100644
> --- a/kernel/bpf/hashtab.c
> +++ b/kernel/bpf/hashtab.c
> @@ -622,6 +622,8 @@ static struct bpf_map *htab_map_alloc(union bpf_attr  
> *attr)
>   free_prealloc:
>   	prealloc_destroy(htab);
>   free_map_locked:
> +	if (htab->use_percpu_counter)
> +		percpu_counter_destroy(&htab->pcount);
>   	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
>   		free_percpu(htab->map_locked[i]);
>   	bpf_map_area_free(htab->buckets);
> --
> 2.18.4