netdev - Re: [PATCH bpf] xsk: fix memory leak for failed bind

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Date:   Mon, 14 Dec 2020 10:45:11 +0100
From:   Björn Töpel <bjorn.topel@...el.com>
To:     Magnus Karlsson <magnus.karlsson@...il.com>,
        magnus.karlsson@...el.com, ast@...nel.org, daniel@...earbox.net,
        netdev@...r.kernel.org, jonathan.lemon@...il.com
Cc:     bpf@...r.kernel.org,
        syzbot+cfa88ddd0655afa88763@...kaller.appspotmail.com
Subject: Re: [PATCH bpf] xsk: fix memory leak for failed bind

On 2020-12-14 09:51, Magnus Karlsson wrote:
> From: Magnus Karlsson <magnus.karlsson@...el.com>
> 
> Fix a possible memory leak when a bind of an AF_XDP socket fails. When
> the fill and completion rings are created, they are tied to the
> socket. But when the buffer pool is later created at bind time, the
> ownership of these two rings are transferred to the buffer pool as
> they might be shared between sockets (and the buffer pool cannot be
> created until we know what we are binding to). So, before the buffer
> pool is created, these two rings are cleaned up with the socket, and
> after they have been transferred they are cleaned up together with
> the buffer pool.
> 
> The problem is that ownership was transferred before it was absolutely
> certain that the buffer pool could be created and initialized
> correctly and when one of these errors occurred, the fill and
> completion rings did neither belong to the socket nor the pool and
> where therefore leaked. Solve this by moving the ownership transfer
> to the point where the buffer pool has been completely set up and
> there is no way it can fail.
> 
> Fixes: 7361f9c3d719 ("xsk: Move fill and completion rings to buffer pool")
> Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
> Reported-by: syzbot+cfa88ddd0655afa88763@...kaller.appspotmail.com

Acked-by: Björn Töpel <bjorn.topel@...el.com>