Commit 30a87f15 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by David S. Miller

net: mlxfw: 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>
Reviewed-by: default avatarJiri Pirko <jiri@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e6a98f80
...@@ -496,7 +496,7 @@ mlxfw_mfa2_file_component_tlv_get(const struct mlxfw_mfa2_file *mfa2_file, ...@@ -496,7 +496,7 @@ mlxfw_mfa2_file_component_tlv_get(const struct mlxfw_mfa2_file *mfa2_file,
struct mlxfw_mfa2_comp_data { struct mlxfw_mfa2_comp_data {
struct mlxfw_mfa2_component comp; struct mlxfw_mfa2_component comp;
u8 buff[0]; u8 buff[];
}; };
static const struct mlxfw_mfa2_tlv_component_descriptor * static const struct mlxfw_mfa2_tlv_component_descriptor *
......
...@@ -11,7 +11,7 @@ struct mlxfw_mfa2_tlv { ...@@ -11,7 +11,7 @@ struct mlxfw_mfa2_tlv {
u8 version; u8 version;
u8 type; u8 type;
__be16 len; __be16 len;
u8 data[0]; u8 data[];
} __packed; } __packed;
static inline const struct mlxfw_mfa2_tlv * static inline const struct mlxfw_mfa2_tlv *
......
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