Unconditionally define __stack_chk_guard [BZ #26817]

__stack_chk_guard is currently unavailable on architectures which define
THREAD_SET_STACK_GUARD, so {gcc,clang} -fstack-protector
-mstack-protector-guard=global will fail to link due to the undefined
symbol.

Define __stack_chk_guard to make -mstack-protector-guard=global compiled
user programs work. `#define THREAD_SET_STACK_GUARD` code is moved
outside of `#ifndef __ASSEMBLER__` so that cpp can preprocess
elf/Versions.

csu/libc-start.c

@@ -33,11 +33,8 @@ extern void __libc_init_first (int argc, char **argv, char **envp);
 #include <tls.h>
 #ifndef SHARED
 # include <dl-osinfo.h>
-# ifndef THREAD_SET_STACK_GUARD
-/* Only exported for architectures that don't store the stack guard canary
-   in thread local area.  */
+/* Also export to architectures which prefer -mstack-protector-guard=tls.  */
 uintptr_t __stack_chk_guard attribute_relro;
-# endif
 # ifndef  THREAD_SET_POINTER_GUARD
 /* Only exported for architectures that don't store the pointer guard
    value in thread local area.  */
@@ -206,9 +203,8 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
   uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
 # ifdef THREAD_SET_STACK_GUARD
   THREAD_SET_STACK_GUARD (stack_chk_guard);
-# else
-  __stack_chk_guard = stack_chk_guard;
 # endif
+  __stack_chk_guard = stack_chk_guard;
 
 # ifdef DL_SYSDEP_OSCHECK
   {

elf/Versions

@@ -1,3 +1,6 @@
+%if __has_include("tls.h")
+%include "tls.h"
+%endif
 libc {
   GLIBC_2.0 {
 %ifdef EXPORT_UNWIND_FIND_FDE
@@ -50,7 +53,15 @@ ld {
   }
   GLIBC_2.4 {
     # stack canary
+%ifndef THREAD_SET_STACK_GUARD
     __stack_chk_guard;
+%endif
+  }
+  GLIBC_2.33 {
+    # stack canary
+%ifdef THREAD_SET_STACK_GUARD
+    __stack_chk_guard;
+%endif
   }
   GLIBC_PRIVATE {
     # Those are in the dynamic linker, but used by libc.so.

elf/rtld.c

@@ -154,11 +154,8 @@ unsigned int _dl_skip_args attribute_relro attribute_hidden;
 #endif
 rtld_hidden_data_def (_dl_argv)
 
-#ifndef THREAD_SET_STACK_GUARD
-/* Only exported for architectures that don't store the stack guard canary
-   in thread local area.  */
+/* Also export to architectures which prefer -mstack-protector-guard=tls.  */
 uintptr_t __stack_chk_guard attribute_relro;
-#endif
 
 /* Only exported for architectures that don't store the pointer guard
    value in thread local area.  */
@@ -865,9 +862,8 @@ security_init (void)
   uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
 #ifdef THREAD_SET_STACK_GUARD
   THREAD_SET_STACK_GUARD (stack_chk_guard);
-#else
-  __stack_chk_guard = stack_chk_guard;
 #endif
+  __stack_chk_guard = stack_chk_guard;
 
   /* Set up the pointer guard as well, if necessary.  */
   uintptr_t pointer_chk_guard

sysdeps/i386/nptl/tls.h

@@ -68,6 +68,13 @@ _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30,
    the SSE memory functions.  */
 #define STACK_ALIGN	16
 
+/* Set the stack guard field in TCB head. Referenced by elf/Versions. */
+#define THREAD_SET_STACK_GUARD(value) \
+  THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
+#define THREAD_COPY_STACK_GUARD(descr) \
+  ((descr)->header.stack_guard						      \
+   = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
+
 #ifndef __ASSEMBLER__
 /* Get system call information.  */
 # include <sysdep.h>
@@ -358,14 +365,6 @@ tls_fill_user_desc (union user_desc_init *desc,
        }})
 
 
-/* Set the stack guard field in TCB head.  */
-#define THREAD_SET_STACK_GUARD(value) \
-  THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
-#define THREAD_COPY_STACK_GUARD(descr) \
-  ((descr)->header.stack_guard						      \
-   = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
-
-
 /* Set the pointer guard field in the TCB head.  */
 #define THREAD_SET_POINTER_GUARD(value) \
   THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)

sysdeps/ia64/nptl/tls.h

@@ -46,6 +46,13 @@ register struct pthread *__thread_self __asm__("r13");
 /* Alignment requirement for the stack.  */
 #define STACK_ALIGN	16
 
+/* Set the stack guard field in TCB head. Referenced by elf/Versions.  */
+#define THREAD_SET_STACK_GUARD(value) \
+  (((uintptr_t *) __thread_self)[-1] = (value))
+#define THREAD_COPY_STACK_GUARD(descr) \
+  (((uintptr_t *) ((char *) (descr) + TLS_PRE_TCB_SIZE))[-1] \
+   = ((uintptr_t *) __thread_self)[-1])
+
 #ifndef __ASSEMBLER__
 /* Get system call information.  */
 # include <sysdep.h>
@@ -138,13 +145,6 @@ register struct pthread *__thread_self __asm__("r13");
 #define THREAD_SETMEM_NC(descr, member, idx, value) \
   descr->member[idx] = (value)
 
-/* Set the stack guard field in TCB head.  */
-#define THREAD_SET_STACK_GUARD(value) \
-  (((uintptr_t *) __thread_self)[-1] = (value))
-#define THREAD_COPY_STACK_GUARD(descr) \
-  (((uintptr_t *) ((char *) (descr) + TLS_PRE_TCB_SIZE))[-1] \
-   = ((uintptr_t *) __thread_self)[-1])
-
 /* Set the pointer guard field in TCB head.  */
 #define THREAD_GET_POINTER_GUARD() \
   (((uintptr_t *) __thread_self)[-2])

sysdeps/mach/hurd/i386/ld.abilist

@@ -16,4 +16,5 @@ GLIBC_2.2.6 _r_debug D 0x14
 GLIBC_2.2.6 abort F
 GLIBC_2.3 ___tls_get_addr F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.33 __stack_chk_guard D 0x4
 GLIBC_2.33 __x86_get_cpu_features F

sysdeps/mach/hurd/i386/tls.h

@@ -79,6 +79,13 @@ typedef struct
    "Segment Base".)  On such machines, a cache line is 64 bytes.  */
 #define TCB_ALIGNMENT		64
 
+/* Set the stack guard field in TCB head. Referenced by elf/Versions.  */
+#define THREAD_SET_STACK_GUARD(value) \
+  THREAD_SETMEM (THREAD_SELF, stack_guard, value)
+#define THREAD_COPY_STACK_GUARD(descr) \
+  ((descr)->stack_guard							      \
+   = THREAD_GETMEM (THREAD_SELF, stack_guard))
+
 #ifndef __ASSEMBLER__
 
 /* Use i386-specific RPCs to arrange that %gs segment register prefix
@@ -296,13 +303,6 @@ out:
      _dtv; })
 
 
-/* Set the stack guard field in TCB head.  */
-#define THREAD_SET_STACK_GUARD(value) \
-  THREAD_SETMEM (THREAD_SELF, stack_guard, value)
-#define THREAD_COPY_STACK_GUARD(descr) \
-  ((descr)->stack_guard							      \
-   = THREAD_GETMEM (THREAD_SELF, stack_guard))
-
 /* Set the pointer guard field in the TCB head.  */
 #define THREAD_SET_POINTER_GUARD(value) \
   THREAD_SETMEM (THREAD_SELF, pointer_guard, value)

sysdeps/powerpc/nptl/tls.h

@@ -33,6 +33,16 @@
 # include <asm/ptrace.h>
 #endif /* __ASSEMBLER__ */
 
+/* Set the stack guard field in TCB head. Used by elf/Versions.  */
+# define THREAD_SET_STACK_GUARD(value) \
+    (((tcbhead_t *) ((char *) __thread_register				      \
+		     - TLS_TCB_OFFSET))[-1].stack_guard = (value))
+# define THREAD_COPY_STACK_GUARD(descr) \
+    (((tcbhead_t *) ((char *) (descr)					      \
+		     + TLS_PRE_TCB_SIZE))[-1].stack_guard		      \
+     = ((tcbhead_t *) ((char *) __thread_register			      \
+		       - TLS_TCB_OFFSET))[-1].stack_guard)
+
 #ifndef __powerpc64__
 /* Register r2 (tp) is reserved by the ABI as "thread pointer". */
 # define PT_THREAD_POINTER PT_R2
@@ -191,16 +201,6 @@ typedef struct
 # define THREAD_SETMEM_NC(descr, member, idx, value) \
     ((void)(descr), (THREAD_SELF)->member[idx] = (value))
 
-/* Set the stack guard field in TCB head.  */
-# define THREAD_SET_STACK_GUARD(value) \
-    (((tcbhead_t *) ((char *) __thread_register				      \
-		     - TLS_TCB_OFFSET))[-1].stack_guard = (value))
-# define THREAD_COPY_STACK_GUARD(descr) \
-    (((tcbhead_t *) ((char *) (descr)					      \
-		     + TLS_PRE_TCB_SIZE))[-1].stack_guard		      \
-     = ((tcbhead_t *) ((char *) __thread_register			      \
-		       - TLS_TCB_OFFSET))[-1].stack_guard)
-
 /* Set the stack guard field in TCB head.  */
 # define THREAD_GET_POINTER_GUARD() \
     (((tcbhead_t *) ((char *) __thread_register				      \

sysdeps/s390/nptl/tls.h

@@ -57,6 +57,18 @@ typedef struct
    the SSE memory functions.  */
 #define STACK_ALIGN	16
 
+/* Set the stack guard field in TCB head. Referenced by elf/Versions.  */
+#define THREAD_SET_STACK_GUARD(value) \
+  do									      \
+   {									      \
+     __asm__ __volatile__ ("" : : : "a0", "a1");			      \
+     THREAD_SETMEM (THREAD_SELF, header.stack_guard, value);		      \
+   }									      \
+  while (0)
+#define THREAD_COPY_STACK_GUARD(descr) \
+  ((descr)->header.stack_guard						      \
+   = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
+
 #ifndef __ASSEMBLER__
 /* Get system call information.  */
 # include <sysdep.h>
@@ -145,18 +157,6 @@ typedef struct
 #define THREAD_SETMEM_NC(descr, member, idx, value) \
   descr->member[idx] = (value)
 
-/* Set the stack guard field in TCB head.  */
-#define THREAD_SET_STACK_GUARD(value) \
-  do									      \
-   {									      \
-     __asm__ __volatile__ ("" : : : "a0", "a1");			      \
-     THREAD_SETMEM (THREAD_SELF, header.stack_guard, value);		      \
-   }									      \
-  while (0)
-#define THREAD_COPY_STACK_GUARD(descr) \
-  ((descr)->header.stack_guard						      \
-   = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
-
 /* s390 doesn't have HP_TIMING_*, so for the time being
    use stack_guard as pointer_guard.  */
 #define THREAD_GET_POINTER_GUARD() \

sysdeps/sparc/nptl/tls.h

@@ -51,6 +51,12 @@ typedef struct
 # include <tcb-offsets.h>
 #endif /* __ASSEMBLER__ */
 
+/* Set the stack guard field in TCB head. Referenced by elf/Versions.  */
+#define THREAD_SET_STACK_GUARD(value) \
+  THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
+# define THREAD_COPY_STACK_GUARD(descr) \
+  ((descr)->header.stack_guard \
+   = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
 
 #ifndef __ASSEMBLER__
 /* Get system call information.  */
@@ -122,13 +128,6 @@ register struct pthread *__thread_self __asm__("%g7");
 #define THREAD_SETMEM_NC(descr, member, idx, value) \
   descr->member[idx] = (value)
 
-/* Set the stack guard field in TCB head.  */
-#define THREAD_SET_STACK_GUARD(value) \
-  THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
-# define THREAD_COPY_STACK_GUARD(descr) \
-  ((descr)->header.stack_guard \
-   = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
-
 /* Get/set the stack guard field in TCB head.  */
 #define THREAD_GET_POINTER_GUARD() \
   THREAD_GETMEM (THREAD_SELF, header.pointer_guard)

sysdeps/unix/sysv/linux/i386/ld.abilist

@@ -3,4 +3,5 @@ GLIBC_2.1 __libc_stack_end D 0x4
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 ___tls_get_addr F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.33 __stack_chk_guard D 0x4
 GLIBC_2.33 __x86_get_cpu_features F

sysdeps/unix/sysv/linux/ia64/ld.abilist

@@ -2,3 +2,4 @@ GLIBC_2.2 __libc_stack_end D 0x8
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x28
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.33 __stack_chk_guard D 0x8

sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist

@@ -4,3 +4,4 @@ GLIBC_2.1 _dl_mcount F
 GLIBC_2.22 __tls_get_addr_opt F
 GLIBC_2.23 __parse_hwcap_and_convert_at_platform F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.33 __stack_chk_guard D 0x4

sysdeps/unix/sysv/linux/powerpc/powerpc64/be/ld.abilist

@@ -4,3 +4,4 @@ GLIBC_2.3 __libc_stack_end D 0x8
 GLIBC_2.3 __tls_get_addr F
 GLIBC_2.3 _dl_mcount F
 GLIBC_2.3 _r_debug D 0x28
+GLIBC_2.33 __stack_chk_guard D 0x8

sysdeps/unix/sysv/linux/powerpc/powerpc64/le/ld.abilist

@@ -4,3 +4,4 @@ GLIBC_2.17 _dl_mcount F
 GLIBC_2.17 _r_debug D 0x28
 GLIBC_2.22 __tls_get_addr_opt F
 GLIBC_2.23 __parse_hwcap_and_convert_at_platform F
+GLIBC_2.33 __stack_chk_guard D 0x8

sysdeps/unix/sysv/linux/s390/s390-32/ld.abilist

@@ -2,3 +2,4 @@ GLIBC_2.0 _r_debug D 0x14
 GLIBC_2.1 __libc_stack_end D 0x4
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 __tls_get_offset F
+GLIBC_2.33 __stack_chk_guard D 0x4

sysdeps/unix/sysv/linux/s390/s390-64/ld.abilist

@@ -2,3 +2,4 @@ GLIBC_2.2 __libc_stack_end D 0x8
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x28
 GLIBC_2.3 __tls_get_offset F
+GLIBC_2.33 __stack_chk_guard D 0x8

sysdeps/unix/sysv/linux/sparc/sparc32/ld.abilist

@@ -2,3 +2,4 @@ GLIBC_2.0 _r_debug D 0x14
 GLIBC_2.1 __libc_stack_end D 0x4
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.33 __stack_chk_guard D 0x4

sysdeps/unix/sysv/linux/sparc/sparc64/ld.abilist

@@ -2,3 +2,4 @@ GLIBC_2.2 __libc_stack_end D 0x8
 GLIBC_2.2 _dl_mcount F
 GLIBC_2.2 _r_debug D 0x28
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.33 __stack_chk_guard D 0x8

sysdeps/unix/sysv/linux/x86_64/64/ld.abilist

@@ -2,4 +2,5 @@ GLIBC_2.2.5 __libc_stack_end D 0x8
 GLIBC_2.2.5 _dl_mcount F
 GLIBC_2.2.5 _r_debug D 0x28
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.33 __stack_chk_guard D 0x8
 GLIBC_2.33 __x86_get_cpu_features F

sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist

@@ -2,4 +2,5 @@ GLIBC_2.16 __libc_stack_end D 0x4
 GLIBC_2.16 __tls_get_addr F
 GLIBC_2.16 _dl_mcount F
 GLIBC_2.16 _r_debug D 0x14
+GLIBC_2.33 __stack_chk_guard D 0x4
 GLIBC_2.33 __x86_get_cpu_features F

sysdeps/x86_64/nptl/tls.h

@@ -94,6 +94,13 @@ _Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x80,
 /* Alignment requirement for the stack.  */
 #define STACK_ALIGN	16
 
+/* Set the stack guard field in TCB head. Used by elf/Versions.  */
+# define THREAD_SET_STACK_GUARD(value) \
+    THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
+# define THREAD_COPY_STACK_GUARD(descr) \
+    ((descr)->header.stack_guard					      \
+     = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
+
 
 #ifndef __ASSEMBLER__
 /* Get system call information.  */
@@ -303,14 +310,6 @@ _Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x80,
        }})
 
 
-/* Set the stack guard field in TCB head.  */
-# define THREAD_SET_STACK_GUARD(value) \
-    THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
-# define THREAD_COPY_STACK_GUARD(descr) \
-    ((descr)->header.stack_guard					      \
-     = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
-
-
 /* Set the pointer guard field in the TCB head.  */
 # define THREAD_SET_POINTER_GUARD(value) \
   THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)