lib/57689: getcwd() not overridable with -D_FORTIFY_SOURCE

[rvp%SDF.ORG@localhost]

>Number:         57689
>Category:       lib
>Synopsis:       getcwd() not overridable with -D_FORTIFY_SOURCE
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Nov 10 00:00:00 +0000 2023
>Originator:     RVP
>Release:        -HEAD, 10.x, 9.x
>Organization:
>Environment:
10.99.10 amd64
>Description:
getcwd() in libc is a weak symbol, but, you can't override it if compiled
with SSP & -O:

```
$ nm -D /lib/libc.so | fgrep getcwd
00000000000aea70 T __getcwd
00000000000a8ae0 T _getcwd
00000000000a8ae0 W _sys_getcwd
00000000000a8ae0 W getcwd
$ cat t.c
#include <err.h>
#include <errno.h>
#include <unistd.h>

char*
getcwd(char* buf, size_t buflen)
{
        errno = ENOSYS;
        return NULL;
}
int
main(void)
{
        char buf[256];  
        if (getcwd(buf, sizeof buf) == NULL)
                err(1, "getcwd failed");
        return 0;
}
$ gcc -O2 -o g g.c
$ ./g
g: getcwd failed: Function not implemented
$ gcc -O2 -D_FORTIFY_SOURCE=2 -o g g.c
g.c:6:1: error: redefinition of ?getcwd?
 getcwd(char* buf, size_t buflen)
 ^~~~~~
In file included from /usr/include/ssp/unistd.h:34:0,
                 from /usr/include/unistd.h:74,
                 from g.c:3:
/usr/include/ssp/unistd.h:45:1: note: previous definition of ?getcwd? was here
 __ssp_redirect_raw(char *, getcwd, getcwd, (char *__buf, size_t __len),
 ^
$
```

Should be pulled up to 10.x, 9.x, 8.x.
>How-To-Repeat:
As above.
>Fix:
Ref: gnu_inline attribute description in:
https://gcc.gnu.org/onlinedocs/gcc-10.5.0/gcc/Common-Function-Attributes.html

```
--- include/ssp/ssp.h.orig	2022-06-29 12:45:25.000000000 +0000
+++ include/ssp/ssp.h	2022-06-30 23:55:56.181039331 +0000
@@ -56,7 +56,7 @@
 #endif
 #define __ssp_real(fun)		__ssp_real_(fun)
 
-#define __ssp_inline static __inline __attribute__((__always_inline__))
+#define __ssp_inline extern __inline __attribute__((__always_inline__, __gnu_inline__))
 
 #define __ssp_bos(ptr) __builtin_object_size(ptr, __SSP_FORTIFY_LEVEL > 1)
 #define __ssp_bos0(ptr) __builtin_object_size(ptr, 0)
```