Initialize the stack guard earlier when linking statically [BZ #7065]

The address of the stack canary is stored in a per-thread variable,
which means that we must ensure that the TLS area is intialized before
calling any -fstack-protector'ed functions.  For dynamically linked
applications, we ensure this (in a later patch) by disabling
-fstack-protector for the whole dynamic linker, but for static
applications, the AT_ENTRY address is called directly by the kernel, so
we must deal with the problem differently.

In static appliations, __libc_setup_tls performs the TCB setup and TLS
initialization, so this commit arranges for it to be called early and
unconditionally.  The call (and the stack guard initialization) is
before the DL_SYSDEP_OSCHECK hook, which if set will probably call
functions which are stack-protected (it does on Linux and NaCL too).  We
also move apply_irel up, so that we can still safely call functions that
require ifuncs while in __libc_setup_tls (though if stack-protection is
enabled we still have to avoid calling functions that are not
stack-protected at this stage).

1 files changed, 11 insertions, 0 deletions

diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 34d7ec152d..bb67840b22 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -994,6 +994,17 @@ extern size_t _dl_count_modids (void) internal_function attribute_hidden;
 /* Calculate offset of the TLS blocks in the static TLS block.  */
 extern void _dl_determine_tlsoffset (void) internal_function attribute_hidden;
 
+#ifndef SHARED
+/* Set up the TCB for statically linked applications.  This is called
+   early during startup because we always use TLS (for errno and the
+   stack protector, among other things).  */
+void __libc_setup_tls (void);
+
+/* Initialization of libpthread for statically linked applications.
+   If libpthread is not linked in, this is an empty function.  */
+void __pthread_initialize_minimal (void) weak_function;
+#endif
+
 /* Allocate memory for static TLS block (unless MEM is nonzero) and dtv.  */
 extern void *_dl_allocate_tls (void *mem) internal_function;
 rtld_hidden_proto (_dl_allocate_tls)