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efi/apple-properties: Replace zero-length array with flexible-array member 

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
inadvertenly introduced[3] to the codebase from now on.

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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200211231421.GA15697@embeddedor
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Gustavo A. R. Silva 2020-02-11 17:14:21 -06:00 committed by Ard Biesheuvel
parent b92165d2ba
commit 3b9274ea1c
1 changed files with 2 additions and 2 deletions
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4
drivers/firmware/efi/apple-properties.c
View File

@ -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,