netdev - Re: [PATCH v2 1/1] xdp: avoid calling kfree twice

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Message-ID: <f68c2d75-4a51-445d-cecf-894b65cb8d55@iogearbox.net>
Date:   Tue, 8 Dec 2020 18:12:44 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Zhu Yanjun <yanjun.zhu@...el.com>, zyjzyj2000@...il.com,
        bjorn.topel@...el.com, magnus.karlsson@...el.com,
        netdev@...r.kernel.org, jonathan.lemon@...il.com
Subject: Re: [PATCH v2 1/1] xdp: avoid calling kfree twice

On 12/9/20 6:03 AM, Zhu Yanjun wrote:
> In the function xdp_umem_pin_pages, if npgs != umem->npgs and
> npgs >= 0, the function xdp_umem_unpin_pages is called. In this
> function, kfree is called to handle umem->pgs, and then in the
> function xdp_umem_pin_pages, kfree is called again to handle
> umem->pgs. Eventually, umem->pgs is freed twice.
> 
> Acked-by: Björn Töpel <bjorn.topel@...el.com>
> Signed-off-by: Zhu Yanjun <yanjun.zhu@...el.com>

Please also fix up the commit log according to Bjorn's prior feedback [0].
If it's just a cleanup, it should state so, the commit message right now
makes it sound like an actual double free bug.

   [0] https://lore.kernel.org/netdev/0fef898d-cf5e-ef1b-6c35-c98669e9e0ed@intel.com/