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>
---
include/linux/dccp.h | 2 +-
net/dccp/ccid.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 6b64b6cc2175..07e547c02fd8 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -198,7 +198,7 @@ enum dccp_role {
struct dccp_service_list {
__u32 dccpsl_nr;
- __be32 dccpsl_list[0];
+ __be32 dccpsl_list[];
};
#define DCCP_SERVICE_INVALID_VALUE htonl((__u32)-1)
diff --git a/net/dccp/ccid.h b/net/dccp/ccid.h
index 70f88f2b4456..105f3734dadb 100644
--- a/net/dccp/ccid.h
+++ b/net/dccp/ccid.h
@@ -95,7 +95,7 @@ void ccid_cleanup_builtins(void);
struct ccid {
struct ccid_operations *ccid_ops;
- char ccid_priv[0];
+ char ccid_priv[];
};
static inline void *ccid_priv(const struct ccid *ccid)
--
2.25.0
