The current codebase makes use of the zero-length array language
extension to the C90 standard, 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, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[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 <gustavo@xxxxxxxxxxxxxx>
---
drivers/acpi/nfit/nfit.h | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index 24241941181c..af09143ce403 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -144,32 +144,32 @@ struct nfit_spa {
unsigned long ars_state;
u32 clear_err_unit;
u32 max_ars;
- struct acpi_nfit_system_address spa[0];
+ struct acpi_nfit_system_address spa[];
};
struct nfit_dcr {
struct list_head list;
- struct acpi_nfit_control_region dcr[0];
+ struct acpi_nfit_control_region dcr[];
};
struct nfit_bdw {
struct list_head list;
- struct acpi_nfit_data_region bdw[0];
+ struct acpi_nfit_data_region bdw[];
};
struct nfit_idt {
struct list_head list;
- struct acpi_nfit_interleave idt[0];
+ struct acpi_nfit_interleave idt[];
};
struct nfit_flush {
struct list_head list;
- struct acpi_nfit_flush_address flush[0];
+ struct acpi_nfit_flush_address flush[];
};
struct nfit_memdev {
struct list_head list;
- struct acpi_nfit_memory_map memdev[0];
+ struct acpi_nfit_memory_map memdev[];
};
enum nfit_mem_flags {
--
2.23.0
