Re: crash bug on closed connection

Some of these steps might not be necessary. It might could be accomplished
with a kill -9 on postgres. I tried running Postgres on Windows, and force
killing it, but then the client always knew the connection was down.

When this occurs "in the wild", it is usually related to a timeout, so the
fix that was checked in recently for setting tcpKeepAlive might be a
workaround.

On Mon, Oct 13, 2014 at 4:44 PM, Jade Koskela <jkoskela0(at)gmail(dot)com> wrote:

> I have been looking into this crash for a while now, and I finally have a
> good repro.
>
> After digging through it with wireshark I observed this
> client tries to send a query
> retransmit query
> retransmit query
> ...
> client sends TCP [RST],[ACK]
> Now it has crashed, so we restart it again and begin another connection
> successfully.
>
> It seems that the connection has dropped, but the client was never
> informed, and it doesn't handle this gracefully.
>
> I reproed it like this:
>
> On my mac running postgres server:
> Setup port forwarding to emulate a proxy or firewall problem
> ssh -L [public ip]:5433:localhost:5432 -N localhost
>
> On my windows machine:
> Connect to port 5433 on my mac
> Run a query
>
> On my mac:
> Kill the ssh proxy
> sighup postgres
> open the ssh proxy again
>
> On my windows machine:
> Run another query (machine still thinks connection is ok)
> Crash in psqlodbcw.dll
>
> > psqlodbc35w.dll!Exec_with_parameters_resolved(StatementClass_ *
> stmt=0x0a6f4fa0, int * exec_end=0x083bf3dc) Line 606 + 0x1b bytes C
> psqlodbc35w.dll!PGAPI_Execute(void * hstmt=0x0a6f4fa0, unsigned short
> flag=1) Line 1147 + 0xd bytes C
> psqlodbc35w.dll!SQLExecute(void * StatementHandle=0x0a6f4fa0) Line 386
> + 0xe bytes C
> odbc32(dot)dll!_SQLExecute(at)4() + 0x2c1 bytes
>
> > if (sscanf(cmd , "UPDATE %d", &count) == 1) // here cmd is junk but not
> null (0xddddddd)
>
>
>
>