Add missing store in emission of asan_stack_free.

gcc/ChangeLog:

2020-05-19  Martin Liska  <mliska@suse.cz>

	PR sanitizer/94910
	* asan.c (asan_emit_stack_protection): Emit
	also **SavedFlagPtr(FakeStack, class_id) = 0 in order to release
	a stack frame.

diff --git a/gcc/asan.c b/gcc/asan.c
index c9872f1b0075ddfb1ddd40dabe707421429d8264..e015fa3ec9b4b33e53a88bbd98b934b711eda239 100644 (file)
--- a/gcc/asan.c
+++ b/gcc/asan.c
@@ -1598,8 +1598,24 @@ asan_emit_stack_protection (rtx base, rtx pbase, unsigned int alignb,
       if (use_after_return_class < 5
          && can_store_by_pieces (sz, builtin_memset_read_str, &c,
                                  BITS_PER_UNIT, true))
-       store_by_pieces (shadow_mem, sz, builtin_memset_read_str, &c,
-                        BITS_PER_UNIT, true, RETURN_BEGIN);
+       {
+         /* Emit:
+              memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
+              **SavedFlagPtr(FakeStack, class_id) = 0
+         */
+         store_by_pieces (shadow_mem, sz, builtin_memset_read_str, &c,
+                          BITS_PER_UNIT, true, RETURN_BEGIN);
+
+         unsigned HOST_WIDE_INT offset
+           = (1 << (use_after_return_class + 6));
+         offset -= GET_MODE_SIZE (ptr_mode);
+         mem = gen_rtx_MEM (ptr_mode, base);
+         mem = adjust_address (mem, ptr_mode, offset);
+         rtx addr = gen_reg_rtx (ptr_mode);
+         emit_move_insn (addr, mem);
+         mem = gen_rtx_MEM (QImode, addr);
+         emit_move_insn (mem, const0_rtx);
+       }
       else if (use_after_return_class >= 5
               || !set_storage_via_setmem (shadow_mem,
                                           GEN_INT (sz),