[Octave-bug-tracker] [bug #30685] Segmentation fault in ./run-octave [sigemptyset() in liboctinterp-3.3.52.so]

[Keith Godfrey]

Follow-up Comment #35, bug #30685 (project octave):

The only breakpoint I can set is in octave_set_signal_handler as the code from
libgnu/sigprocmask.c is not compiled. Stepping into the linked version of
sigemptyset at the assembly level, and typing "where" generates the stack
trace below. The subsequent stepi crashes. 

(gdb) 
0x00002af563822de8 in sigemptyset ()
   from
/global/home/keith/software/octave-3.4.0/src/.libs/liboctinterp-3.4.0.so
1: x/3i $pc
0x2af563822de8 <sigemptyset>:   callq  0x2af558e5b01a
0x2af563822ded <sigemptyset+5>: sub    (%rax),%al
0x2af563822def <sigemptyset+7>: add    %dh,%al
(gdb) where
#0  0x00002af563822de8 in sigemptyset ()
   from
/global/home/keith/software/octave-3.4.0/src/.libs/liboctinterp-3.4.0.so
#1  0x00002af562ddfb11 in octave_set_signal_handler (sig=2, 
    handler=0x2af562de0080 <sigint_handler>, restart_syscalls=true)
    at sighandlers.cc:233
#2  0x00002af562ddfbda in octave_catch_interrupts () at sighandlers.cc:467
#3  0x00002af562ddfc43 in install_signal_handlers () at sighandlers.cc:536
#4  0x00002af562db2577 in octave_main (argc=6, argv=0x7fffca36c0b8,
embedded=0)
    at octave.cc:665
#5  0x0000003cc421d994 in __libc_start_main () from /lib64/libc.so.6
#6  0x00000000004006a9 in _start ()
(gdb) 


excerpt from 'nm liboctinterp-3.4.0.so' :

0000000001009df0 d sigaction
0000000001009df8 d sigaddset
0000000001009de8 d sigemptyset
0000000001009e00 d sigprocmask

I don't know if this might be helpful, or simply add noise as I'm way outside
of my element here, but the instruction at the address of sigemptyset are not
consistent between runs. The 3 instructions associated with sigemptyset seem
to be, but not after. Also, these instructions don't appear to be consistent
with function calls - e.g., no returns

0x2ae09f511de8 <sigemptyset>:   callq  0x2ae07ff06f0a
0x2ae09f511ded <sigemptyset+5>: sub    (%rax),%al
0x2ae09f511def <sigemptyset+7>: add    %dh,%al
0x2ae09f511df1 <sigaction+1>:   sbb    $0x2ae09f51,%eax
0x2ae09f511df6 <sigaction+6>:   add    %al,(%rax)
0x2ae09f511df8 <sigaddset>:     clc    

0x2b9236b10de8 <sigemptyset>:   callq  0x2b91c8e7befa
0x2b9236b10ded <sigemptyset+5>: sub    (%rax),%eax
0x2b9236b10def <sigemptyset+7>: add    %dh,%al
0x2b9236b10df1 <sigaction+1>:   or     $0x2b9236b1,%eax
0x2b9236b10df6 <sigaction+6>:   add    %al,(%rax)
0x2b9236b10df8 <sigaddset>:     clc    

0x2b93c0259de8 <sigemptyset>:   callq  0x2b9353e5c38a
0x2b93c0259ded <sigemptyset+5>: sub    (%rax),%eax
0x2b93c0259def <sigemptyset+7>: add    %dh,%al
0x2b93c0259df1 <sigaction+1>:   popfq  
0x2b93c0259df2 <sigaction+2>:   and    $0x2b93c0,%eax
0x2b93c0259df7 <sigaction+7>:   add    %bh,%al
0x2b93c0259df9 <sigaddset+1>:   popfq  



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