netdev - Re: [PATCH bpf] bpf: fix missing prog untrack in release

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Date:   Mon, 16 Dec 2019 18:52:02 +0000
From:   Yonghong Song <yhs@...com>
To:     Daniel Borkmann <daniel@...earbox.net>,
        "alexei.starovoitov@...il.com" <alexei.starovoitov@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf] bpf: fix missing prog untrack in release_maps



On 12/16/19 8:49 AM, Daniel Borkmann wrote:
> Commit da765a2f5993 ("bpf: Add poke dependency tracking for prog array
> maps") wrongly assumed that in case of prog load errors, we're cleaning
> up all program tracking via bpf_free_used_maps().
> 
> However, it can happen that we're still at the point where we didn't copy
> map pointers into the prog's aux section such that env->prog->aux->used_maps
> is still zero, running into a UAF. In such case, the verifier has similar
> release_maps() helper that drops references to used maps from its env.
> 
> Consolidate the release code into __bpf_free_used_maps() and call it from
> all sides to fix it.
> 
> Fixes: da765a2f5993 ("bpf: Add poke dependency tracking for prog array maps")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>

Acked-by: Yonghong Song <yhs@...com>