]> git.baikalelectronics.ru Git - kernel.git/commit
ACPICA: Replace one-element array with flexible-array
authorGustavo A. R. Silva <gustavoars@kernel.org>
Mon, 20 Jul 2020 17:31:19 +0000 (10:31 -0700)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Mon, 27 Jul 2020 12:55:42 +0000 (14:55 +0200)
commit914afd9ecf073811e908f7689ff584ab58db6e08
tree49fef4c18607bd775cc027f0c202b8bf9e6b917d
parentcd194de09f766ecaa52d957318a77257f18d3584
ACPICA: Replace one-element array with flexible-array

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 4287773bdd7a ("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>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
drivers/acpi/acpica/utids.c
include/acpi/actypes.h