Re: my app segfault, but why?

[Helmethead <hoshem mel comcen com au>]

On Mon, Mar 26, 2001 at 01:51:24AM +0200, Ronald Bultje wrote:
> Hey there,
> 
> I have the problem that after a few minutes of use (generally after 5 to 30
> minutes), my application dumps core with a segfault. The core doesn't say
> much, neither does running the app itself in gdb. All I get is:
> 
> (gdb) run
> Starting program: /home/rbultje/studio 
> [New Thread 1024 (LWP 786)]
> 
> (here, I run the program for several minutes...)
> 
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 1024 (LWP 786)]
> 0x40160016 in parent_class () from /usr/lib/libgdk-1.2.so.0
> (gdb) bt
> #0  0x40160016 in parent_class () from /usr/lib/libgdk-1.2.so.0
> #1  0x900 in ?? ()
> Cannot access memory at address 0xd202020
> (gdb)
> 
> For as far as I know, the only part where I explicitely use gdk is in
> drawing a V4L/xvideo-extension area in a GdkDrawable using the xvideo
> extension in X. But other apps on internet use that too and they don't
> crash... Does gtk itself use gdk implicitely (I never studied gtk/gdk that
> deeply yet)? And what could cause such a crash after these several minutes?
> I read something about buffer overflows if I read about this topic on
> internet... Could this be the cause?
> 
> I hope someone can give me some light on this.
> Many thanks in advance,
> 
> Ronald Bultje

gtk is based on gdk, -all- it's interactions with the underlying windowing system are done with gdk :)

Something has apparently screwed over your stack. Some kind of buffer overflow could have done it yeah. I think whatever went wrong happened in that place in gdk though. I dunno where that parent_class symbol came from, there's no function called parent_class only variables, and in my gdk none of them are exported. What kind of system are you running? Maybe your gdk doesn't have debugging symbols and you might try building one that does.