gdb bug report

[Debian User]

I've found a SegFault in the `gdb'.
When I tried to debug a progrz this appear:

----------------------------------------------------------------------------------------

address@hidden:~/asm/test$ gdb -q opm
(no debugging symbols found)
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) run
Starting program: /home/blecp/asm/test/opm

Program received signal SIGSEGV, Segmentation fault.
0x00000003 in ?? ()
(gdb) i r
eax            0x3      3
ecx            0x0      0
edx            0x4      4
ebx            0x0      0
esp            0xbffffa04       0xbffffa04
ebp            0x0      0x0
esi            0x0      0
edi            0x0      0
eip            0x3      0x3
eflags         0x10206  66054
cs             0x23     35
ss             0x2b     43
ds             0x2b     43
es             0x2b     43
fs             0x0      0
gs             0x0      0
(gdb) disas prev
Dump of assembler code for function prev:
0x08048079 <prev+0>:    pop    %eax
0x0804807a <prev+1>:    add    $0x2,%al
0x0804807c <prev+3>:    push   %eax
0x0804807d <prev+4>:    ret
End of assembler dump.
(gdb) b a
Breakpoint 1 at 0x804807e
(gdb) run
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /home/blecp/asm/test/opm

Breakpoint 1, 0x0804807e in a ()
(gdb) i r
eax            0x0      0
ecx            0x0      0
edx            0x0      0
ebx            0x0      0
esp            0xbffff9fc       0xbffff9fc
ebp            0x0      0x0
esi            0x0      0
edi            0x0      0
eip            0x804807e        0x804807e
eflags         0x246    582
cs             0x23     35
ss             0x2b     43
ds             0x2b     43
es             0x2b     43
fs             0x0      0
gs             0x0      0
(gdb) s
Single stepping until exit from function a,
which has no line number information.
0x08048079 in prev ()
(gdb) i r
eax            0x0      0
ecx            0x0      0
edx            0x0      0
ebx            0x0      0
esp            0xbffff9fc       0xbffff9fc
ebp            0x0      0x0
esi            0x0      0
edi            0x0      0
eip            0x8048079        0x8048079
eflags         0x346    838
cs             0x23     35
ss             0x2b     43
ds             0x2b     43
es             0x2b     43
fs             0x0      0
gs             0x0      0
(gdb) s
Single stepping until exit from function prev,
which has no line number information.

Breakpoint 1, 0x0804807e in a ()
(gdb) i r
eax            0x804807b        134512763
ecx            0x0      0
edx            0x4      4
ebx            0x0      0
esp            0xbffffa00       0xbffffa00
ebp            0x0      0x0
esi            0x0      0
edi            0x0      0
eip            0x804807e        0x804807e
eflags         0x302    770
cs             0x23     35
ss             0x2b     43
ds             0x2b     43
es             0x2b     43
fs             0x0      0
gs             0x0      0
(gdb) s
Single stepping until exit from function a,
which has no line number information.
0x08048079 in prev ()
(gdb) i r
eax            0x804807b        134512763
ecx            0x0      0
edx            0x4      4
ebx            0x0      0
esp            0xbffffa00       0xbffffa00
ebp            0x0      0x0
esi            0x0      0
edi            0x0      0
eip            0x8048079        0x8048079
eflags         0x302    770
cs             0x23     35
ss             0x2b     43
ds             0x2b     43
es             0x2b     43
fs             0x0      0
gs             0x0      0
(gdb) s
Single stepping until exit from function prev,
which has no line number information.
Segmentation fault

---------------------------------------------------------------------------------------------------

My input for gdb was:

run
i r
disas prev
b a
run
// at this question, y
i r
s
i r
s
i r
s
i r
s

Then a nice SEGFAULT :>

The progrz is listed below.

---------------------------------------------------------------------------------------------------

.text
       .globl _start
_start:
       call a
prev:
       popl %eax
       addb $0x2, %al
       pushl %eax
       ret
a:
       jmp prev
       xor %eax, %eax
       movl %eax, %ebx
       movb $1, %al
       movb $7, %bl
       int $0x80

--------------------------------------------------------------------------------------------------

Assembled with `as -o opm.u opm.S' and linked with `ld -o opm opm.u'.

As info:

$ as --version
GNU assembler 2.15
Copyright 2002 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License.  This program has absolutely no warranty.
This assembler was configured for a target of `i386-linux'.

Ld info:

$ ld --version
GNU ld version 2.15
Copyright 2002 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License.  This program has absolutely no warranty.

Gdb info:

$ gdb -v
GNU gdb 6.3-debian
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain 
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-linux".

System info:

Distro: Debian, Stable

$ cat /proc/version
Linux version 2.4.32 (address@hidden) (gcc version 3.3.5 (Debian 1:3.3.5-13)) 
#3 SMP Fri Dec 23 21:14:11 CET 2005
$ cat /proc/cpuinfo
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 6
model           : 10
model name      : AMD Athlon(tm)
stepping        : 0
cpu MHz         : 2004.578
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov pat pse36 mmx fxsr sse syscall mp mmxext 3dnowext 3dnow
bogomips        : 3997.69

And the Glibc 2.2.4.
                                                                                 
oh, and the gdb is really super :>,
                                                                                               
address@hidden