xiaoxiang781216 commented on a change in pull request #1558:
URL: https://github.com/apache/incubator-nuttx/pull/1558#discussion_r468570685
##########
File path: libs/libc/stdlib/lib_stackchk.c
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@@ -0,0 +1,60 @@
+/****************************************************************************
+ * libs/libc/stdlib/lib_stackchk.c
Review comment:
> * how does it fail?
This is link error from arm:
```
arm-none-eabi-ld:
/home/xiaoxiang/nuttx/nuttx/staging/libarch.a(stm32_can.o):(.rodata.cst4+0x0):
undefined reference to `__stack_chk_guard'
```
> * how do you ensure eg. host-privided __stack_chk_fail is not used?
>
From the x86 dissamble code:
```
000000000000b571 <__stack_chk_fail>:
* None.
*
****************************************************************************/
void __stack_chk_fail(void)
{
b571: 55 push %rbp
b572: 48 89 e5 mov %rsp,%rbp
b575: 48 83 ec 10 sub $0x10,%rsp
b579: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
b580: 00 00
b582: 48 89 45 f8 mov %rax,-0x8(%rbp)
b586: 31 c0 xor %eax,%eax
PANIC();
b588: be 39 00 00 00 mov $0x39,%esi
b58d: 48 8d 3d 68 0c 03 00 lea 0x30c68(%rip),%rdi #
3c1fc <g_nullstring+0xd8>
b594: e8 72 04 00 00 callq ba0b <_assert>
```
> even today, when building sim for macOS, ssp things are on by default in
the host cc and ./nuttx is linked with host-provided __stack_chk_fail etc.
> is the situation different for linux?
Yes, Linux will link libssp.a by default too, but it isn't a big issue to
provide our implementation to overwrite the default one. Actually, it's good to
run the same code for simulator and the real hardware.
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