On Tue, Feb 23, 2021 at 10:42 AM Martin Liška <mli...@suse.cz> wrote:
>
> Hello.
>
> The patch is about confusion that brings ICF when it merged 2 variables
> with different alignments (when ASAN is used).
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>
> Ready to be installed?
Can't we fix the asan runtime? Does the same issue happen when merging
two comdat with different alignment and LTO?
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
> PR sanitizer/99168
> * ipa-icf.c (sem_variable::merge): Do not merge 2 variables
> with different alignment. That leads to an invalid red zone
> size allocated in runtime.
>
> gcc/testsuite/ChangeLog:
>
> PR sanitizer/99168
> * c-c++-common/asan/pr99168.c: New test.
> ---
> gcc/ipa-icf.c | 13 ++++++++++++
> gcc/testsuite/c-c++-common/asan/pr99168.c | 26 +++++++++++++++++++++++
> 2 files changed, 39 insertions(+)
> create mode 100644 gcc/testsuite/c-c++-common/asan/pr99168.c
>
> diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c
> index 687ad8d45b7..5dd33a75c3a 100644
> --- a/gcc/ipa-icf.c
> +++ b/gcc/ipa-icf.c
> @@ -88,6 +88,7 @@ along with GCC; see the file COPYING3. If not see
> #include "tree-vector-builder.h"
> #include "symtab-thunks.h"
> #include "alias.h"
> +#include "asan.h"
>
> using namespace ipa_icf_gimple;
>
> @@ -2022,6 +2023,18 @@ sem_variable::merge (sem_item *alias_item)
> return false;
> }
>
> + if (DECL_ALIGN (original->decl) != DECL_ALIGN (alias->decl)
> + && (sanitize_flags_p (SANITIZE_ADDRESS, original->decl)
> + || sanitize_flags_p (SANITIZE_ADDRESS, alias->decl)))
> + {
> + if (dump_enabled_p ())
> + dump_printf (MSG_MISSED_OPTIMIZATION,
> + "Not unifying; "
> + "ASAN requires equal alignments for original and
> alias\n");
> +
> + return false;
> + }
> +
> if (DECL_ALIGN (original->decl) < DECL_ALIGN (alias->decl))
> {
> if (dump_enabled_p ())
> diff --git a/gcc/testsuite/c-c++-common/asan/pr99168.c
> b/gcc/testsuite/c-c++-common/asan/pr99168.c
> new file mode 100644
> index 00000000000..ed59ffb3d48
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/asan/pr99168.c
> @@ -0,0 +1,26 @@
> +/* PR sanitizer/99168 */
> +/* { dg-do run } */
> +
> +struct my_struct
> +{
> + unsigned long volatile x;
> +} __attribute__((aligned(128)));
> +
> +static int variablek[5][6] = {};
> +static struct my_struct variables1 = {0UL};
> +static struct my_struct variables2 __attribute__((aligned(32))) = {0UL};
> +
> +int main() {
> + int i, j;
> + for (i = 0; i < 5; i++) {
> + for (j = 0; j < 6; j++) {
> + __builtin_printf("%d ", variablek[i][j]);
> + }
> + }
> + __builtin_printf("\n");
> +
> + __builtin_printf("%lu\n", variables1.x);
> + __builtin_printf("%lu\n", variables2.x);
> +
> + return 0;
> +}
> --
> 2.30.1
>
