[Devel] [PATCH vz10 5/6] ms/selftests/mm: fix -Warray-bounds warnings in pkey_sighandler_tests

[Vasileios Almpanis]

Reviewed-by: Vasileios Almpanis <vasileios.almpanis at virtuozzo.com>

On 3/23/26 9:29 PM, Konstantin Khorenko wrote:
> From: Kevin Brodsky <kevin.brodsky at arm.com>
>
> GCC doesn't like dereferencing a pointer set to 0x1 (when building
> at -O2):
>
> pkey_sighandler_tests.c:166:9: warning: array subscript 0 is outside array bounds of 'int[0]' [-Warray-bounds=]
>    166 |         *(int *) (0x1) = 1;
>        |         ^~~~~~~~~~~~~~
> cc1: note: source object is likely at address zero
>
> Using NULL instead seems to make it happy.  This should make no difference
> in practice (SIGSEGV with SEGV_MAPERR will be the outcome regardless), we
> just need to update the expected si_addr.
>
> [kevin.brodsky at arm.com: fix clang dereferencing-null issue]
>    Link: https://lkml.kernel.org/r/20241218153615.2267571-1-kevin.brodsky@arm.com
> Link: https://lkml.kernel.org/r/20241209095019.1732120-5-kevin.brodsky@arm.com
> Signed-off-by: Kevin Brodsky <kevin.brodsky at arm.com>
> Cc: Aruna Ramakrishna <aruna.ramakrishna at oracle.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Dave Hansen <dave.hansen at linux.intel.com>
> Cc: Joey Gouly <joey.gouly at arm.com>
> Cc: Keith Lucas <keith.lucas at oracle.com>
> Cc: Ryan Roberts <ryan.roberts at arm.com>
> Cc: Shuah Khan <shuah at kernel.org>
> Cc: kernel test robot <lkp at intel.com>
> Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
>
> (cherry picked from commit 71384f84cbbe7660023b01c1a0fa9cc7dbc487a7)
> Conflict in pkey_sighandler_tests.c: removed unused `int *bad` variable
> declaration — our branch already uses hardcoded pkey_reg values instead
> of pkey_reg_restrictive_default(), so neither `int *bad` nor `u64 pkey_reg`
> are needed.
>
> https://virtuozzo.atlassian.net/browse/VSTOR-127529
> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
>
> Feature: fix selftests
> ---
>   tools/testing/selftests/mm/pkey_sighandler_tests.c | 9 ++++-----
>   1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
> index a8088b645ad6..62f2ab8b440a 100644
> --- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
> +++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
> @@ -116,7 +116,7 @@ static void *thread_segv_with_pkey0_disabled(void *ptr)
>   	__write_pkey_reg(0x55555555);
>   
>   	/* Segfault (with SEGV_MAPERR) */
> -	*(int *) (0x1) = 1;
> +	*(volatile int *)NULL = 1;
>   	return NULL;
>   }
>   
> @@ -132,7 +132,6 @@ static void *thread_segv_pkuerr_stack(void *ptr)
>   static void *thread_segv_maperr_ptr(void *ptr)
>   {
>   	stack_t *stack = ptr;
> -	int *bad = (int *)1;
>   
>   	/*
>   	 * Setup alternate signal stack, which should be pkey_mprotect()ed by
> @@ -145,7 +144,7 @@ static void *thread_segv_maperr_ptr(void *ptr)
>   	__write_pkey_reg(0x55555551);
>   
>   	/* Segfault */
> -	*bad = 1;
> +	*(volatile int *)NULL = 1;
>   	syscall_raw(SYS_exit, 0, 0, 0, 0, 0, 0);
>   	return NULL;
>   }
> @@ -184,7 +183,7 @@ static void test_sigsegv_handler_with_pkey0_disabled(void)
>   
>   	ksft_test_result(siginfo.si_signo == SIGSEGV &&
>   			 siginfo.si_code == SEGV_MAPERR &&
> -			 siginfo.si_addr == (void *)1,
> +			 siginfo.si_addr == NULL,
>   			 "%s\n", __func__);
>   }
>   
> @@ -296,7 +295,7 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void)
>   
>   	ksft_test_result(siginfo.si_signo == SIGSEGV &&
>   			 siginfo.si_code == SEGV_MAPERR &&
> -			 siginfo.si_addr == (void *)1,
> +			 siginfo.si_addr == NULL,
>   			 "%s\n", __func__);
>   }
>