From: David Miller <davem@davemloft.net>
To: john.fastabend@gmail.com
Cc: borkmann@iogearbox.net, ast@kernel.org, netdev@vger.kernel.org
Subject: Re: [bpf PATCH 3/3] bpf: sockmap, fix error handling in redirect failures
Date: Wed, 02 May 2018 14:51:52 -0400 (EDT) [thread overview]
Message-ID: <20180502.145152.30281601337299502.davem@davemloft.net> (raw)
In-Reply-To: <20180502174737.17875.74031.stgit@john-Precision-Tower-5810>
From: John Fastabend <john.fastabend@gmail.com>
Date: Wed, 02 May 2018 10:47:37 -0700
> When a redirect failure happens we release the buffers in-flight
> without calling a sk_mem_uncharge(), the uncharge is called before
> dropping the sock lock for the redirecte, however we missed updating
> the ring start index. When no apply actions are in progress this
> is OK because we uncharge the entire buffer before the redirect.
> But, when we have apply logic running its possible that only a
> portion of the buffer is being redirected. In this case we only
> do memory accounting for the buffer slice being redirected and
> expect to be able to loop over the BPF program again and/or if
> a sock is closed uncharge the memory at sock destruct time.
>
> With an invalid start index however the program logic looks at
> the start pointer index, checks the length, and when seeing the
> length is zero (from the initial release and failure to update
> the pointer) aborts without uncharging/releasing the remaining
> memory.
>
> The fix for this is simply to update the start index. To avoid
> fixing this error in two locations we do a small refactor and
> remove one case where it is open-coded. Then fix it in the
> single function.
>
> Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
next prev parent reply other threads:[~2018-05-02 18:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-02 17:47 [bpf PATCH 0/3] sockmap error path fixes John Fastabend
2018-05-02 17:47 ` [bpf PATCH 1/3] bpf: sockmap, fix scatterlist update on error path in send with apply John Fastabend
2018-05-02 18:51 ` David Miller
2018-05-02 17:47 ` [bpf PATCH 2/3] bpf: sockmap, zero sg_size on error when buffer is released John Fastabend
2018-05-02 18:51 ` David Miller
2018-05-02 17:47 ` [bpf PATCH 3/3] bpf: sockmap, fix error handling in redirect failures John Fastabend
2018-05-02 18:51 ` David Miller [this message]
2018-05-02 19:34 ` Alexei Starovoitov
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