From: Erik Kaneda <erik.kaneda@intel.com>
To: "Rafael J . Wysocki" <rafael@kernel.org>, linux-acpi@vger.kernel.org
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>,
Erik Kaneda <erik.kaneda@intel.com>,
Bob Moore <robert.moore@intel.com>
Subject: [PATCH 1/3] ACPICA: Replace one-element array with flexible-array
Date: Mon, 20 Jul 2020 10:31:19 -0700 [thread overview]
Message-ID: <20200720173121.2580755-2-erik.kaneda@intel.com> (raw)
In-Reply-To: <20200720173121.2580755-1-erik.kaneda@intel.com>
From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
ACPICA commit 7ba2f3d91a32f104765961fda0ed78b884ae193d
The current codebase makes use of one-element arrays in the following
form:
struct something {
int length;
u8 data[1];
};
struct something *instance;
instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL);
instance->length = size;
memcpy(instance->data, source, size);
but the preferred mechanism to declare variable-length types such as
these ones is a flexible array member[1][2], introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure,
which will help us prevent some kind of undefined behavior bugs from
being inadvertently introduced[3] to the linux codebase from now on.
This issue was found with the help of Coccinelle and audited _manually_.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Link: https://github.com/acpica/acpica/commit/7ba2f3d9
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Erik Kaneda <erik.kaneda@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
---
drivers/acpi/acpica/utids.c | 3 +--
include/acpi/actypes.h | 2 +-
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/acpi/acpica/utids.c b/drivers/acpi/acpica/utids.c
index 3bb06935a2ad..3e68864ef242 100644
--- a/drivers/acpi/acpica/utids.c
+++ b/drivers/acpi/acpica/utids.c
@@ -263,8 +263,7 @@ acpi_ut_execute_CID(struct acpi_namespace_node *device_node,
* 3) Size of the actual CID strings
*/
cid_list_size = sizeof(struct acpi_pnp_device_id_list) +
- ((count - 1) * sizeof(struct acpi_pnp_device_id)) +
- string_area_size;
+ (count * sizeof(struct acpi_pnp_device_id)) + string_area_size;
cid_list = ACPI_ALLOCATE_ZEROED(cid_list_size);
if (!cid_list) {
diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
index d005e35ab399..d50e61384f1f 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -1146,7 +1146,7 @@ struct acpi_pnp_device_id {
struct acpi_pnp_device_id_list {
u32 count; /* Number of IDs in Ids array */
u32 list_size; /* Size of list, including ID strings */
- struct acpi_pnp_device_id ids[1]; /* ID array */
+ struct acpi_pnp_device_id ids[]; /* ID array */
};
/*
--
2.25.1
next prev parent reply other threads:[~2020-07-20 17:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 17:31 [PATCH 0/3] ACPICA release 20200717 Erik Kaneda
2020-07-20 17:31 ` Erik Kaneda [this message]
2020-07-20 17:31 ` [PATCH 2/3] ACPICA: Do not increment operation_region reference counts for field units Erik Kaneda
2020-07-20 17:31 ` [PATCH 3/3] ACPICA: Update version to 20200717 Version 20200717 Erik Kaneda
2020-07-27 12:56 ` [PATCH 0/3] ACPICA release 20200717 Rafael J. Wysocki
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