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 Wed, 22 Jul 2020 12:57:12 +0300 (MSK)
Date: Wed, 22 Jul 2020 12:46:53 +0300
From: Igor Munkin <imun@tarantool.org>
Message-ID: <20200722094653.GL18920@tarantool.org>
References: <20200721223242.24467-1-i.kosarev@tarantool.org>
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Subject: Re: [Tarantool-patches] [PATCH v3] lua: assert in lua_gettop() in
 case of negative stack size
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To: Ilya Kosarev <i.kosarev@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org

Ilya,

On 22.07.20, Ilya Kosarev wrote:
> 
> Hi!
> 
> Thanks to @igormunkin we discovered more details of this problem.
> Turns out we can see lua_State stored in port and it seems that
> something is totally wrong here: it points to some function address
> (port_lua_dump_16()). Thus I will make some more research into it and
> this patch should be discarded for now.
> (gdb) p ((struct port_lua *)port)->vtab
> $19 = (const port_vtab *) 0x4e759f <port_lua_dump>
> (gdb) p ((struct port_lua *)port)->L
> $20 = (lua_State *) 0x4e75c9 <port_lua_dump_16>

I've just noticed: port is a stucture, not a pointer, so the values are
totally irrelevant. I guess you need something like this:
| ((struct port_lua *)&port)->L

Could you please share the results for the right dereference?

>   

<snipped>

>  
> --
> Ilya Kosarev
>  

-- 
Best regards,
IM