segmentation fault when stepping multi-threaded application

[Tomas Alvarez Vanoli]

> Is it only when using gdbserver, or does it also happen when using gdb directly on the board ?

It also happens when using gdb directly on the board. Hadn't tested it because we don't have gdb in the target, but I included it and this is the result:

(gdb) break ../sysdeps/powerpc/powerpc32/dl-start.S:32
warning: could not convert '../sysdeps/powerpc/powerpc32/dl-start.S' from the host encoding (ANSI_X3.4-1968) to UTF-32.
This normally should not happen, please file a bug report.
No source file named ../sysdeps/powerpc/powerpc32/dl-start.S.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (../sysdeps/powerpc/powerpc32/dl-start.S:32) pending.
(gdb) run
Starting program: /home/root/tomcli 

Breakpoint 1, _start () at ../sysdeps/powerpc/powerpc32/dl-start.S:32
warning: 32     ../sysdeps/powerpc/powerpc32/dl-start.S: No such file or directory
(gdb) s
35      in ../sysdeps/powerpc/powerpc32/dl-start.S
(gdb) s
36      in ../sysdeps/powerpc/powerpc32/dl-start.S
(gdb) s
_start () at ../sysdeps/powerpc/powerpc32/dl-start.S:40
40      in ../sysdeps/powerpc/powerpc32/dl-start.S
(gdb) s
41      in ../sysdeps/powerpc/powerpc32/dl-start.S
(gdb) s
_dl_start (arg=0xbffffd80) at rtld.c:536
warning: 536    rtld.c: No such file or directory
(gdb) s
538     in rtld.c
(gdb) c
Continuing.
tomcli[153]: User access of kernel address (dffcff10) - exploit attempt? (uid: 0)

Program received signal SIGSEGV, Segmentation fault.
0xb7fe5dd8 in _dl_sysdep_parse_arguments (args=0xbffff9f8, 
    start_argptr=0xdffcff10)
    at /usr/src/debug/glibc/2.39+git/sysdeps/unix/sysv/linux/dl-sysdep.c:80
warning: 80     /usr/src/debug/glibc/2.39+git/sysdeps/unix/sysv/linux/dl-sysdep.c: No such file or directory
(gdb) bt
#0  0xb7fe5dd8 in _dl_sysdep_parse_arguments (args=0xbffff9f8, 
    start_argptr=0xdffcff10)
    at /usr/src/debug/glibc/2.39+git/sysdeps/unix/sysv/linux/dl-sysdep.c:80
#1  _dl_sysdep_start (start_argptr=start_argptr at entry=0xdffcff10, 
    dl_main=0xb7fe7f70 <dl_main>)
    at /usr/src/debug/glibc/2.39+git/sysdeps/unix/sysv/linux/dl-sysdep.c:107
#2  0xb7fe705c in _dl_start_final (arg=arg at entry=0xdffcff10, 
    info=info at entry=0xbffffa90) at rtld.c:494
#3  0xb7fe7724 in _dl_start (arg=0xdffcff10) at rtld.c:583
#4  0xb7fec240 in _start () at ../sysdeps/powerpc/powerpc32/dl-start.S:41
(gdb)

Tomas Alvarez Vanoli
R&D Embedded Software Developer