On Tue, Jan 10, 2012 at 3:14 PM, Tijl Coosemans <t...@coosemans.org> wrote:
> On targets where libc implements stack protector functions (GNU libc,
> FreeBSD libc), and where gcc (as an optimisation) generates calls to
> a locally defined __stack_chk_fail_local instead of directly calling
> the global function __stack_chk_fail (e.g. -fpic code on i386), one
> must explicitly specify -lssp_nonshared or "-lc -lc_nonshared" on the
> command line to statically link in __stack_chk_fail_local.
>
> It would be more convenient if the compiler kept the details of this
> target specific optimisation hidden by passing -lssp_nonshared to the
> linker internally.
>
> Here's a simple test case that shows the problem on i386-freebsd, but
> works just fine on e.g. x86_64 targets:
>
> % cat test.c
> int
> main( void ) {
> return( 0 );
> }
> % gcc46 -o test test.c -fstack-protector-all -fPIE
> /var/tmp//ccjYQxKu.o: In function `main':
> test.c:(.text+0x37): undefined reference to `__stack_chk_fail_local'
> /usr/local/bin/ld: test: hidden symbol `__stack_chk_fail_local' isn't defined
> /usr/local/bin/ld: final link failed: Bad value
> collect2: ld returned 1 exit status
>
>
> I don't have commit access, so please commit when approved.
Works fine for me on i?86-linux without -lssp_nonshared (which I do not
have, so linking would fail).
Richard.
> 2011-01-10 Tijl Coosemans <t...@coosemans.org>
>
> * gcc.c [TARGET_LIBC_PROVIDES_SSP] (LINK_SSP_SPEC): Add
> -lssp_nonshared.
>
> --- gcc/gcc.c.orig
> +++ gcc/gcc.c
> @@ -602,7 +602,7 @@ proper position among the other output f
>
> #ifndef LINK_SSP_SPEC
> #ifdef TARGET_LIBC_PROVIDES_SSP
> -#define LINK_SSP_SPEC "%{fstack-protector:}"
> +#define LINK_SSP_SPEC
> "%{fstack-protector|fstack-protector-all:-lssp_nonshared}"
> #else
> #define LINK_SSP_SPEC
> "%{fstack-protector|fstack-protector-all:-lssp_nonshared -lssp}"
> #endif
