From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Robert Moore <robert.moore@intel.com>,
Erik Kaneda <erik.kaneda@intel.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org, devel@acpica.org,
linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
Kees Cook <keescook@chromium.org>
Subject: [PATCH] ACPICA: Replace one-element array and use struct_size() helper
Date: Mon, 18 May 2020 17:27:22 -0500 [thread overview]
Message-ID: <20200518222722.GA7791@embeddedor> (raw)
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 codebase from now on.
Also, make use of the new struct_size() helper to properly calculate the
size of struct acpi_pnp_device_id_list.
This issue was found with the help of Coccinellea and, audited and
fixed _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")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/acpi/acpica/utids.c | 4 +---
include/acpi/actypes.h | 2 +-
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/acpi/acpica/utids.c b/drivers/acpi/acpica/utids.c
index 3bb06935a2ad3..c2f819a39424a 100644
--- a/drivers/acpi/acpica/utids.c
+++ b/drivers/acpi/acpica/utids.c
@@ -262,9 +262,7 @@ acpi_ut_execute_CID(struct acpi_namespace_node *device_node,
* 2) Size of the CID PNP_DEVICE_ID array +
* 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;
+ cid_list_size = struct_size(cid_list, ids, count) + 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 4defed58ea338..c7bcda0ad366a 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -1145,7 +1145,7 @@ 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 */
};
/*
--
2.26.2
next reply other threads:[~2020-05-18 22:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-18 22:27 Gustavo A. R. Silva [this message]
2020-05-19 10:25 ` [PATCH] ACPICA: Replace one-element array and use struct_size() helper Rafael J. Wysocki
2020-05-19 22:50 ` Gustavo A. R. Silva
2020-05-20 9:15 ` Rafael J. Wysocki
2020-05-20 15:40 ` Kees Cook
2020-05-21 17:30 ` Kaneda, Erik
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