linux-kernel - [PATCH 04/14] selftests/mm: Fix -Warray-bounds warnings in pkey_sighandler

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Message-ID: <20241209095019.1732120-5-kevin.brodsky@arm.com>
Date: Mon,  9 Dec 2024 09:50:09 +0000
From: Kevin Brodsky <kevin.brodsky@....com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org,
	Kevin Brodsky <kevin.brodsky@....com>,
	akpm@...ux-foundation.org,
	aruna.ramakrishna@...cle.com,
	catalin.marinas@....com,
	dave.hansen@...ux.intel.com,
	joey.gouly@....com,
	keith.lucas@...cle.com,
	ryan.roberts@....com,
	shuah@...nel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kselftest@...r.kernel.org,
	x86@...nel.org
Subject: [PATCH 04/14] selftests/mm: Fix -Warray-bounds warnings in pkey_sighandler_tests

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.

Signed-off-by: Kevin Brodsky <kevin.brodsky@....com>
---
 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 c593a426341c..e7b91794f184 100644
--- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
+++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
@@ -163,7 +163,7 @@ static void *thread_segv_with_pkey0_disabled(void *ptr)
 	__write_pkey_reg(pkey_reg_restrictive_default());
 
 	/* Segfault (with SEGV_MAPERR) */
-	*(int *) (0x1) = 1;
+	*(int *)NULL = 1;
 	return NULL;
 }
 
@@ -179,7 +179,6 @@ static void *thread_segv_pkuerr_stack(void *ptr)
 static void *thread_segv_maperr_ptr(void *ptr)
 {
 	stack_t *stack = ptr;
-	int *bad = (int *)1;
 	u64 pkey_reg;
 
 	/*
@@ -195,7 +194,7 @@ static void *thread_segv_maperr_ptr(void *ptr)
 	__write_pkey_reg(pkey_reg);
 
 	/* Segfault */
-	*bad = 1;
+	*(int *)NULL = 1;
 	syscall_raw(SYS_exit, 0, 0, 0, 0, 0, 0);
 	return NULL;
 }
@@ -234,7 +233,7 @@ 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__);
 }
 
@@ -349,7 +348,7 @@ 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__);
 }
 
-- 
2.47.0