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

Thu Feb 2 19:20:00 GMT 2006

David Daney writes:
 > Andrew Haley wrote:
 > > 
 > > 000000a0 0000001c 000000a4 FDE cie=00000000 pc=000000ec..00000121
 > > LOC CFA r5 ra 
 > > 000000ec r4+4 u c-4 
 > > 000000ed r4+8 c-8 c-4 
 > > 000000ef r5+8 c-8 c-4 
 > > 
 > > So, after the instruction at location 0xef the CFA (Caller Frame
 > > Address) is at r5 (AKA %ebp) + 8, the previous r5 (AKA %ebp) is saved
 > > at CFA - 8, and RA (Return Address) is at CFA - 4.
 > > 
 > > That looks right to me. I'm guessing that the unwinder never found
 > > this info.
 > > 
 > Yeah, on linux/glibc it uses dl_iterate_pheader() (sp?) to find 
 > infromation about the loaded objects from there it can find the 
 > .eh_frame sections.
We can test that. tsuraan, please replace that access via a null
pointer with simply
 throw new NullPointerException();
Andrew.