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* [Bug c/39218] New: a surprising instance of -fstack-protector not protecting
@ 2009-02-17 18:58 paul at g225066096 dot adsl dot alicedsl dot de
2009-02-17 19:09 ` [Bug c/39218] " pinskia at gcc dot gnu dot org
2009-04-16 20:43 ` [Bug middle-end/39218] " pinskia at gcc dot gnu dot org
0 siblings, 2 replies; 3+ messages in thread
From: paul at g225066096 dot adsl dot alicedsl dot de @ 2009-02-17 18:58 UTC (permalink / raw)
To: gcc-bugs
$ 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
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/39218] a surprising instance of -fstack-protector not protecting
2009-02-17 18:58 [Bug c/39218] New: a surprising instance of -fstack-protector not protecting paul at g225066096 dot adsl dot alicedsl dot de
@ 2009-02-17 19:09 ` pinskia at gcc dot gnu dot org
2009-04-16 20:43 ` [Bug middle-end/39218] " pinskia at gcc dot gnu dot org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2009-02-17 19:09 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pinskia at gcc dot gnu dot org 2009-02-17 19:08 -------
http://gcc.gnu.org/onlinedocs/gcc-4.3.3/gcc/Optimize-Options.html#index-fstack_002dprotector-764
Hmm:
Emit extra code to check for buffer overflows, such as stack smashing attacks.
This is done by adding a guard variable to functions with vulnerable objects.
This includes functions that call alloca, and functions with buffers larger
than 8 bytes.
Maybe it should say character buffers rather than just buffers here.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39218
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/39218] a surprising instance of -fstack-protector not protecting
2009-02-17 18:58 [Bug c/39218] New: a surprising instance of -fstack-protector not protecting paul at g225066096 dot adsl dot alicedsl dot de
2009-02-17 19:09 ` [Bug c/39218] " pinskia at gcc dot gnu dot org
@ 2009-04-16 20:43 ` pinskia at gcc dot gnu dot org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2009-04-16 20:43 UTC (permalink / raw)
To: gcc-bugs
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |documentation
Last reconfirmed|0000-00-00 00:00:00 |2009-04-16 20:43:45
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39218
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-02-17 18:58 [Bug c/39218] New: a surprising instance of -fstack-protector not protecting paul at g225066096 dot adsl dot alicedsl dot de
2009-02-17 19:09 ` [Bug c/39218] " pinskia at gcc dot gnu dot org
2009-04-16 20:43 ` [Bug middle-end/39218] " pinskia at gcc dot gnu dot org
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