git problems

[Ed Schouten]

* Peter Jeremy <peterjeremy at optushome.com.au> wrote:
> On 2008-Jun-04 11:26:02 -0400, Chuck Robey <chuckr at telenix.org> wrote:
> >#3  0x08066467 in unlock_pack () at builtin-fetch.c:56
> >#4  0x2848b5f3 in __cxa_finalize () from /lib/libc.so.7
> >#5  0x2843b1aa in exit () from /lib/libc.so.7
> >#6  0x0804b0e3 in handle_internal_command (argc=2, argv=0xffffffff) at git.c:379
> >#7  0x0804b7ed in main (argc=2, argv=Cannot access memory at address 0x12) at git.c:414
> 
> __cxa_finalise() is part of the atexit() processing - the source comments
> imply it handles shared object destructors.
> 
> >379                     exit(run_command(p, argc, argv));
> >380             }
> >
> >First I want to comment on that weird line 379, because while it
> >might work, it sure seems to me to be a very strange and wasteful way
> >to do a fork.
> 
> There's no fork involved.  It's just shorthand for:
> 	return_code = run_command(p, argc, argv);
> 	exit(return_code);
> By the time exit() is invoked, run_command() has completed.
> 
> >  Second, the second argument to handle_internal_command seems to
> >have been a argv=0xffffffff, which is very obviously a bad string
> >pointer
> 
> Note that argv in main is also corrupt.  I suspect gdb is confused by
> the level of optimisation being done by gcc.
> 
> In a later posting, you indicate that there's a double-free bug.
> Possibly unlock_pack() is being registered as a destructor (or
> similar) _and_ is being explicitly called.  Without studying the
> code, the solution is probably to either skip the explicit cleanup
> (leaving just the destructor processing) and/or flag freed data (ie
> NULL pointers after freeing them).

I just solved this on my systems by removing the call to free(). I know,
it's awful, but it was good enough for me to live with on short term.

-- 
 Ed Schouten <ed at 80386.nl>
 WWW: http://80386.nl/
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