[Discuss-gnuradio] Weird malloc/free crash in pm_remez.cc

[Josh Myer]

Hi all,

I’ve got an annoying crash in the current head of gnuradio.  It’s reproducible 
with the GRC file up at:

http://www.joshisanerd.com/am_demod_crash.grc

Does this crash for anyone else?  If nobody else can repro, this is probably 
something that’s hosed in my environment.  Until someone else can confirm this, 
it’s probably not worth looking into for anyone else.

For me, the crash is at pm_remez.cc:698, the free(Grid) call in the error 
handler.  (It’s coming from an error code of -2, which is probably due to my 
putting in totally insane parameters or some such.)

The odd thing is that it doesn’t look like it should be crashing in this code 
path.  The pointer it’s freeing is totally fine when I step through with gdb: 
the same as the malloc’d value, and no intervening free() calls, yet it’s still 
crashing when it gets free()’d.  When I move the free(Grid) line around, the 
crash follows it.  It doesn’t look like anything else is getting screwed up, so 
I don’t know what to make of this.

(FWIW, my goal is to poke around at decoding RDS.  I’ve removed a lot of stuff 
to get down to this minimal program that shows the problem.  I’ve gotten the AM 
demod stuff sorta working in ipython, and am now trying to port it back to 
gnuradio… pointers on anything that’s clearly wrong with my design there would 
be appreciated.)
—
/jbm