[re] Java executables can abort trying to access a null pointer in a leaf function

David Daney ddaney@avtrex.com
Thu Feb 2 18:17:00 GMT 2006


Andrew Haley wrote:
> David Daney writes:
>  > Andrew Haley wrote:
>  > > tsuraan writes:
>  > >  > > Someone will need the assembly and/or object file for a small test case
>  > >  > > to examine the DWARF frame data.
>  > >  > 
>  > >  > I can send a tarball of the entire directory, if desired.  It's 14 KB
>  > >  > without the core dump and 1.2MB with it.  I don't know what filesize
>  > >  > starts to anger people on this list, so I'll just send the smaller
>  > >  > tarball for now.  If the core is desired, I can send that too.
>  > > 
>  > > This looks OK to me: we are generating te null pointer check.  
>  > > 
>  > > Until we actually see the faulting instruction in gdb we're not going
>  > > to get anywhere.  Just load your program into gdb, run it, and tel us
>  > > when it hits the SEGV.
>  > > 
>  > 
>  > Uh, I don't think there was a fault.  There is an explicit call to 
>  > _Jv_ThrowNullPointerException, then we abort because the unwinder fails.
> 
> That's what I'm trying to prove.
> 
> I think there is probably bad debuginfo for
> NullPointer.foo(NullPointer).  Looking at the backtrace in gdb will
> give us a good idea.
> 
The stacktrace that tsuraan supplied shows that the abort happens at the 
abort() at the bottom of _Jv_Throw, exactly were it happened to me a 
while ago when I had bad .eh_frame data.

David Daney.



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