On Wed, Jan 25, 2023 at 05:49:20PM -0800, Andrew Pinski wrote:
> On Wed, Jan 25, 2023 at 3:26 PM Marek Polacek via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > 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.
>
> I am trying to follow the code but I can't tell if -fsanitize=address
> -fno-sanitize=address still will work?
> It would make sense to add a testcase for that case too.
>
> I suspect it does not work though, because it would still leave
> SANITIZE_ADDRESS enabled ...
You're totally right; I was trying to be clever and didn't consider
that case. I should have kept the code simple and straightforward,
like below.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/12/11?
-- >8 --
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.
---
gcc/opts.cc | 9 ++++++++-
.../c-c++-common/asan/pointer-subtract-5.c | 15 +++++++++++++++
.../c-c++-common/asan/pointer-subtract-6.c | 15 +++++++++++++++
.../c-c++-common/asan/pointer-subtract-7.c | 15 +++++++++++++++
.../c-c++-common/asan/pointer-subtract-8.c | 15 +++++++++++++++
5 files changed, 68 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/c-c++-common/asan/pointer-subtract-5.c
create mode 100644 gcc/testsuite/c-c++-common/asan/pointer-subtract-6.c
create mode 100644 gcc/testsuite/c-c++-common/asan/pointer-subtract-7.c
create mode 100644 gcc/testsuite/c-c++-common/asan/pointer-subtract-8.c
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;
+}
base-commit: a2dddefeed258119fc24d288b697d58da9e8b7e3
--
2.39.1
