$ cc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ./configure --prefix=/gcc
Thread model: posix
gcc version 4.3.3 (GCC)
$ echo 'void f(void) { char buf[50]; g(buf); }' > 1.c
$ echo 'void f(void) { int buf[50]; g(buf); }' > 2.c
$ cc -fstack-protector -c 1.c # protects
$ cc -fstack-protector -c 2.c # does not protect
$ objdump -d 1.o
1.o: file format elf32-i386
Disassembly of section .text:
00000000 <f>:
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 83 ec 48 sub $0x48,%esp
6: 65 a1 14 00 00 00 mov %gs:0x14,%eax
c: 89 45 fc mov %eax,-0x4(%ebp)
f: 31 c0 xor %eax,%eax
11: 8d 45 ca lea -0x36(%ebp),%eax
14: 89 04 24 mov %eax,(%esp)
17: e8 fc ff ff ff call 18 <f+0x18>
1c: 8b 45 fc mov -0x4(%ebp),%eax
1f: 65 33 05 14 00 00 00 xor %gs:0x14,%eax
26: 74 05 je 2d <f+0x2d>
28: e8 fc ff ff ff call 29 <f+0x29>
2d: c9 leave
2e: c3 ret
$ objdump -d 2.o
2.o: file format elf32-i386
Disassembly of section .text:
00000000 <f>:
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 81 ec d8 00 00 00 sub $0xd8,%esp
9: 8d 85 38 ff ff ff lea -0xc8(%ebp),%eax
f: 89 04 24 mov %eax,(%esp)
12: e8 fc ff ff ff call 13 <f+0x13>
17: c9 leave
18: c3 ret
$
--
Summary: a surprising instance of -fstack-protector not
protecting
Product: gcc
Version: 4.3.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: paul at g225066096 dot adsl dot alicedsl dot de
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39218
