Re: [lwip-users] RAW PCB disconnected

[Sylvain Rochet]

Hi Frédéric,


On Mon, Jul 25, 2016 at 05:17:37AM +0000, Frédéric Grandjean wrote:
> Dear community members,
> 
> I need your lights about a behavior of LwIP;
> 
> We just solved an issue in our app, in RAW mode, when a PCB was 
> disconnected (RESET) by the remote host. In that case, the bug was we 
> called the tcp_close function anyway.
> 
> This led to a strange behavior, where the PCB management (chained 
> list) finally looped the same PCB to itself, ending in an endless 
> loop.
> 
> In the beginning this looked like an issue in LwIP. Of course, finally 
> it was just in our app! But I would say there is a weakness in the 
> stack in that case !?
> 
> What's your opinion about this?

That's a use after free programming error, behavior is then undefined. 


> How can I make sure this kind of scenario won't happen again ?

Well, don't do use after free :-)


Sylvain

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