Commit 06ccf63d authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva

tpm_eventlog.h: 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
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 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: default avatarGustavo A. R. Silva <gustavo@embeddedor.com>
parent 4ea19ecf
......@@ -28,7 +28,7 @@ struct tcpa_event {
u32 event_type;
u8 pcr_value[20]; /* SHA1 */
u32 event_size;
u8 event_data[0];
u8 event_data[];
};
enum tcpa_event_types {
......@@ -55,7 +55,7 @@ enum tcpa_event_types {
struct tcpa_pc_event {
u32 event_id;
u32 event_size;
u8 event_data[0];
u8 event_data[];
};
enum tcpa_pc_event_ids {
......@@ -102,7 +102,7 @@ struct tcg_pcr_event {
struct tcg_event_field {
u32 event_size;
u8 event[0];
u8 event[];
} __packed;
struct tcg_pcr_event2_head {
......
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