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/firmware/efi/apple-properties.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/firmware/efi/apple-properties.c b/drivers/firmware/efi/apple-properties.c
index 5ccf39986a14..084942846f4d 100644
--- a/drivers/firmware/efi/apple-properties.c
+++ b/drivers/firmware/efi/apple-properties.c
@@ -31,7 +31,7 @@ __setup("dump_apple_properties", dump_properties_enable);
struct dev_header {
u32 len;
u32 prop_count;
- struct efi_dev_path path[0];
+ struct efi_dev_path path[];
/*
* followed by key/value pairs, each key and value preceded by u32 len,
* len includes itself, value may be empty (in which case its len is 4)
@@ -42,7 +42,7 @@ struct properties_header {
u32 len;
u32 version;
u32 dev_count;
- struct dev_header dev_header[0];
+ struct dev_header dev_header[];
};
static void __init unmarshal_key_value_pairs(struct dev_header *dev_header,
--
2.25.0
