[gcc r13-5399] opts: SANITIZE_ADDRESS wrongly cleared [PR108543]

[Marek Polacek <mpolacek@gcc.gnu.org>]

https://gcc.gnu.org/g:a82ce9c8d155ecda2d1c647d5c588f29e21ef4a3

commit r13-5399-ga82ce9c8d155ecda2d1c647d5c588f29e21ef4a3
Author: Marek Polacek <polacek@redhat.com>
Date:   Wed Jan 25 17:19:54 2023 -0500

    opts: SANITIZE_ADDRESS wrongly cleared [PR108543]
    
    Here we crash on a null fndecl ultimately because we haven't defined
    the built-ins described in sanitizer.def.  So
    builtin_decl_explicit (BUILT_IN_ASAN_POINTER_SUBTRACT);
    returns NULL_TREE, causing an ICE later.
    
    DEF_SANITIZER_BUILTIN only actually defines the built-ins when flag_sanitize
    has SANITIZE_ADDRESS, or some of the other SANITIZE_*, but it doesn't check
    SANITIZE_KERNEL_ADDRESS or SANITIZE_USER_ADDRESS.  Unfortunately, with
    -fsanitize=address -fno-sanitize=kernel-address
    or
    -fsanitize=kernel-address -fno-sanitize=address
    SANITIZE_ADDRESS ends up being unset from flag_sanitize even though
    _USER/_KERNEL are set.  That's because -fsanitize=address means
    SANITIZE_ADDRESS | SANITIZE_USER_ADDRESS and -fsanitize=kernel-address
    is SANITIZE_ADDRESS | SANITIZE_KERNEL_ADDRESS but parse_sanitizer_options
    does
      flags &= ~sanitizer_opts[i].flag;
    so the subsequent -fno- unsets SANITIZE_ADDRESS.  Then no sanitizer
    built-ins are actually defined.
    
    I'm not sure why SANITIZE_ADDRESS isn't just SANITIZE_USER_ADDRESS |
    SANITIZE_KERNEL_ADDRESS, I don't think we need 3 bits.
    
            PR middle-end/108543
    
    gcc/ChangeLog:
    
            * opts.cc (parse_sanitizer_options): Don't always clear SANITIZE_ADDRESS
            if it was previously set.
    
    gcc/testsuite/ChangeLog:
    
            * c-c++-common/asan/pointer-subtract-5.c: New test.
            * c-c++-common/asan/pointer-subtract-6.c: New test.
            * c-c++-common/asan/pointer-subtract-7.c: New test.
            * c-c++-common/asan/pointer-subtract-8.c: New test.

Diff:
---
 gcc/opts.cc                                          |  9 ++++++++-
 gcc/testsuite/c-c++-common/asan/pointer-subtract-5.c | 15 +++++++++++++++
 gcc/testsuite/c-c++-common/asan/pointer-subtract-6.c | 15 +++++++++++++++
 gcc/testsuite/c-c++-common/asan/pointer-subtract-7.c | 15 +++++++++++++++
 gcc/testsuite/c-c++-common/asan/pointer-subtract-8.c | 15 +++++++++++++++
 5 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/gcc/opts.cc b/gcc/opts.cc
index 9ba47d7deaa..a032cd4ce58 100644
--- a/gcc/opts.cc
+++ b/gcc/opts.cc
@@ -2246,7 +2246,14 @@ parse_sanitizer_options (const char *p, location_t loc, int scode,
 		  flags |= sanitizer_opts[i].flag;
 	      }
 	    else
-	      flags &= ~sanitizer_opts[i].flag;
+	      {
+		flags &= ~sanitizer_opts[i].flag;
+		/* Don't always clear SANITIZE_ADDRESS if it was previously
+		   set: -fsanitize=address -fno-sanitize=kernel-address should
+		   leave SANITIZE_ADDRESS set.  */
+		if (flags & (SANITIZE_KERNEL_ADDRESS | SANITIZE_USER_ADDRESS))
+		  flags |= SANITIZE_ADDRESS;
+	      }
 	    found = true;
 	    break;
 	  }
diff --git a/gcc/testsuite/c-c++-common/asan/pointer-subtract-5.c b/gcc/testsuite/c-c++-common/asan/pointer-subtract-5.c
new file mode 100644
index 00000000000..867eda0e61e
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/pointer-subtract-5.c
@@ -0,0 +1,15 @@
+/* PR middle-end/108543 */
+/* { dg-do compile  } */
+/* { dg-options "-fsanitize=address -fno-sanitize=kernel-address -fsanitize=pointer-subtract" } */
+
+struct S {
+  long _M_p;
+};
+
+typedef struct S S;
+
+__PTRDIFF_TYPE__
+f (S __x, S __y)
+{
+  return &__x._M_p - &__y._M_p;
+}
diff --git a/gcc/testsuite/c-c++-common/asan/pointer-subtract-6.c b/gcc/testsuite/c-c++-common/asan/pointer-subtract-6.c
new file mode 100644
index 00000000000..785b90b3d98
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/pointer-subtract-6.c
@@ -0,0 +1,15 @@
+/* PR middle-end/108543 */
+/* { dg-do compile  } */
+/* { dg-options "-fsanitize=kernel-address -fno-sanitize=address -fsanitize=pointer-subtract" } */
+
+struct S {
+  long _M_p;
+};
+
+typedef struct S S;
+
+__PTRDIFF_TYPE__
+f (S __x, S __y)
+{
+  return &__x._M_p - &__y._M_p;
+}
diff --git a/gcc/testsuite/c-c++-common/asan/pointer-subtract-7.c b/gcc/testsuite/c-c++-common/asan/pointer-subtract-7.c
new file mode 100644
index 00000000000..11b63401b8c
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/pointer-subtract-7.c
@@ -0,0 +1,15 @@
+/* PR middle-end/108543 */
+/* { dg-do compile  } */
+/* { dg-options "-fno-sanitize=kernel-address -fsanitize=address -fsanitize=pointer-subtract" } */
+
+struct S {
+  long _M_p;
+};
+
+typedef struct S S;
+
+__PTRDIFF_TYPE__
+f (S __x, S __y)
+{
+  return &__x._M_p - &__y._M_p;
+}
diff --git a/gcc/testsuite/c-c++-common/asan/pointer-subtract-8.c b/gcc/testsuite/c-c++-common/asan/pointer-subtract-8.c
new file mode 100644
index 00000000000..ac2b9c3c1d9
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/pointer-subtract-8.c
@@ -0,0 +1,15 @@
+/* PR middle-end/108543 */
+/* { dg-do compile  } */
+/* { dg-options "-fno-sanitize=address -fsanitize=kernel-address -fsanitize=pointer-subtract" } */
+
+struct S {
+  long _M_p;
+};
+
+typedef struct S S;
+
+__PTRDIFF_TYPE__
+f (S __x, S __y)
+{
+  return &__x._M_p - &__y._M_p;
+}