On Wed, Nov 23, 2016 at 12:37:12PM -0700, Jeff Ross wrote:
> Hi all,
>
> I've got a program that seg faults on OpenBSD 6.0 AMD64 release that runs
> fine on 5.9 i386.
>
> I'm checking to see if will also run on 5.9 AMD64 right now but it doesn't
> appear to be w^x related. To be sure I've mounted that partition with
> wxallowed.
>
> Here are the last few lines from kdump--would sure appreciate it if someone
> could shed some light on what's happening.
>
> 47868 fastforward CALL
> mmap(0,0x1000,0x3<PROT_READ|PROT_WRITE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
> 47868 fastforward RET mmap 9049032314880/0x83ae45b5000
> 47868 fastforward CALL
> mmap(0,0x1000,0x3<PROT_READ|PROT_WRITE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
> 47868 fastforward RET mmap 9049215606784/0x83aef482000
> 47868 fastforward CALL
> mmap(0,0xa000,0x3<PROT_READ|PROT_WRITE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
> 47868 fastforward RET mmap 9047796883456/0x83a9ab82000
> 47868 fastforward CALL mprotect(0x83b09fd2000,0x1000,0x1<PROT_READ>)
> 47868 fastforward RET mprotect 0
> 47868 fastforward CALL munmap(0x83a9ab82000,0xa000)
> 47868 fastforward RET munmap 0
> 47868 fastforward CALL mprotect(0x83870f07000,0x1000,0x1<PROT_READ>)
> 47868 fastforward RET mprotect 0
> 47868 fastforward CALL getthrid()
> 47868 fastforward RET getthrid 1047868/0xffd3c
> 47868 fastforward CALL __set_tcb(0x83b14ce3600)
> 47868 fastforward RET __set_tcb 0
> 47868 fastforward CALL
> mmap(0,0x1000,0x3<PROT_READ|PROT_WRITE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
> 47868 fastforward RET mmap 9049102131200/0x83ae884a000
> 47868 fastforward CALL mprotect(0x83ae884a000,0x1000,0x1<PROT_READ>)
> 47868 fastforward RET mprotect 0
> 47868 fastforward CALL
> mprotect(0x83ae884a000,0x1000,0x3<PROT_READ|PROT_WRITE>)
> 47868 fastforward RET mprotect 0
> 47868 fastforward CALL mprotect(0x83ae884a000,0x1000,0x1<PROT_READ>)
> 47868 fastforward RET mprotect 0
> 47868 fastforward CALL sigaction(SIGPIPE,0x7f7ffffcdec0,0)
> 47868 fastforward STRU struct sigaction { handler=SIG_IGN, mask=0<>,
> flags=0<> }
> 47868 fastforward RET sigaction 0
> 47868 fastforward PSIG SIGSEGV SIG_DFL code SEGV_MAPERR<1> addr=0x71008620
> trapno=6
> 47868 fastforward NAMI "fastforward.core"
The program is aborted by a SIGSEGV. Thta means it is accessing a
memory location that is not allocated by the program.
>
> I've re-compiled this also with what I found on the internet to make a core
> file that gdb can use but that's even more of a mystery to me than ktrace.
> Is there a better debugger that I can use?
>
> Thanks,
>
> Jeff Ross
$ gdb fastforward fastforward.core
then type the command bt, should give you some clue, if the stack isn't
damaged too much.
-Otto
