rtld: do not allow both dynamic DTV index and static TLS offset

If we are allocating static offset for an object with dynamic index,
return failure.  In the opposite case, if dynamic index is requested for
statically allocated TLS area, directly use the offset instead of
setting the index.

Taken from NetBSD Joerg Sonnenberger change for src/libexec/ld.elf_so/tls.c
rev. 1.18.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

libexec/rtld-elf/rtld.c

@@ -5463,6 +5463,17 @@ allocate_module_tls(int index)
 		rtld_die();
 	}
 
+	if (obj->tls_static) {
+#ifdef TLS_VARIANT_I
+		p = (char *)_tcb_get() + obj->tlsoffset;
+#else
+		p = (char *)_tcb_get() - obj->tlsoffset;
+#endif
+		return (p);
+	}
+
+	obj->tls_dynamic = true;
+
 	p = malloc_aligned(obj->tlssize, obj->tlsalign, obj->tlspoffset);
 	memcpy(p, obj->tlsinit, obj->tlsinitsize);
 	memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
@@ -5474,6 +5485,9 @@ allocate_tls_offset(Obj_Entry *obj)
 {
     size_t off;
 
+    if (obj->tls_dynamic)
+	return (false);
+
     if (obj->tls_static)
 	return (true);
 

libexec/rtld-elf/rtld.h

@@ -246,6 +246,7 @@ typedef struct Struct_Obj_Entry {
     bool jmpslots_done : 1;	/* Already have relocated the jump slots */
     bool init_done : 1;		/* Already have added object to init list */
     bool tls_static : 1;	/* Already allocated offset for static TLS */
+    bool tls_dynamic : 1;	/* A non-static DTV entry has been allocated */
     bool phdr_alloc : 1;	/* Phdr is allocated and needs to be freed. */
     bool z_origin : 1;		/* Process rpath and soname tokens */
     bool z_nodelete : 1;	/* Do not unload the object and dependencies */