Subject: Re: [RFC PATCH v3 00/17] Return of smart HTTP

From: "Shawn O. Pearce" <[email-masked]>
Date: Thu, 15 Oct 2009 08:41:42 -0700

Johan Herland <[email-masked]> wrote:
> Don't have time to look into this at the moment, but a cursory gdb
> shows that the "git fetch" in test #4 in t9801 segfaults with the
> following stacktrace:
> 
> #0  0x00007f8dd67e8a47 in fclose () from /lib/libc.so.6
> #1  0x00000000004a05b5 in disconnect_helper (transport=<value optimized out>) at transport-helper.c:81
> #2  0x000000000049de1e in transport_disconnect (transport=0x1955490) at transport.c:952
> #3  0x0000000000423477 in cmd_fetch (argc=26566704, argv=0x0, prefix=<value optimized out>) at builtin-fetch.c:748
> #4  0x0000000000404233 in handle_internal_command (argc=2, argv=0x7fffdf293d20) at git.c:251
> #5  0x0000000000404426 in main (argc=2, argv=0x7fffdf293d20) at git.c:438

It does.  It is caused by the disconnect_helper call inside of
fetch_with_import.  You can't disconnect inside of the fetch method
of a transport, the caller is going to disconnect you a second time.

During that second disconnect the transport->data field is now
pointing at a garbage area of memory.  We're passing a garbage
pointer from data->out to fclose, and fclose is rightly upset.

This bug isn't due to the merge, its a bug in Johan's series that
needs to be fixed before it could merge down to next/master.

-- 
Shawn.