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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Linux ACPI <linux-acpi@vger.kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Bob Moore <robert.moore@intel.com>,
        Kees Cook <kees@outflux.net>
Subject: [PATCH 29/32] ACPICA: acpi_resource_irq: Replace 1-element arrays with flexible array
Date:   Wed, 05 Apr 2023 15:56:59 +0200
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From: Kees Cook <kees@outflux.net>

ACPICA commit bfdd3446e7caf795c85c70326c137023942972c5

Similar to "Replace one-element array with flexible-array", replace the
1-element array with a proper flexible array member as defined by C99.

This allows the code to operate without tripping compile-time and run-
time bounds checkers (e.g. via __builtin_object_size(), -fsanitize=bounds,
and/or -fstrict-flex-arrays=3). Note that the spec requires there be at
least one interrupt, so use a union to keep space allocated for this.

The only binary change in .text and .data sections is some rearrangement
by the compiler of acpi_dm_address_common(), but appears to be harmless.

Link: https://github.com/acpica/acpica/commit/bfdd3446
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/acpica/amlresrc.h |  5 ++++-
 include/acpi/acrestyp.h        | 10 ++++++++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/acpica/amlresrc.h b/drivers/acpi/acpica/amlresrc.h
index 48df447ef5bb..4e88f9fc2a28 100644
--- a/drivers/acpi/acpica/amlresrc.h
+++ b/drivers/acpi/acpica/amlresrc.h
@@ -261,7 +261,10 @@ struct aml_resource_address16 {
 struct aml_resource_extended_irq {
 	AML_RESOURCE_LARGE_HEADER_COMMON u8 flags;
 	u8 interrupt_count;
-	u32 interrupts[1];
+	union {
+		u32 interrupt;
+		 ACPI_FLEX_ARRAY(u32, interrupts);
+	};
 	/* res_source_index, res_source optional fields follow */
 };
 
diff --git a/include/acpi/acrestyp.h b/include/acpi/acrestyp.h
index 4c3b7b393f82..b84cd316217f 100644
--- a/include/acpi/acrestyp.h
+++ b/include/acpi/acrestyp.h
@@ -142,7 +142,10 @@ struct acpi_resource_irq {
 	u8 shareable;
 	u8 wake_capable;
 	u8 interrupt_count;
-	u8 interrupts[1];
+	union {
+		u8 interrupt;
+		 ACPI_FLEX_ARRAY(u8, interrupts);
+	};
 };
 
 struct acpi_resource_dma {
@@ -335,7 +338,10 @@ struct acpi_resource_extended_irq {
 	u8 wake_capable;
 	u8 interrupt_count;
 	struct acpi_resource_source resource_source;
-	u32 interrupts[1];
+	union {
+		u32 interrupt;
+		 ACPI_FLEX_ARRAY(u32, interrupts);
+	};
 };
 
 struct acpi_resource_generic_register {
-- 
2.35.3