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

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Gustavo A. R. Silva 2020-02-24 10:36:52 -06:00 committed by David S. Miller
parent f49b275982
commit 3f6e963305
6 changed files with 12 additions and 12 deletions

View File

@ -104,14 +104,14 @@ struct cmsg_req_map_op {
__be32 tid;
__be32 count;
__be32 flags;
u8 data[0];
u8 data[];
};
struct cmsg_reply_map_op {
struct cmsg_reply_map_simple reply_hdr;
__be32 count;
__be32 resv;
u8 data[0];
u8 data[];
};
struct cmsg_bpf_event {
@ -120,6 +120,6 @@ struct cmsg_bpf_event {
__be64 map_ptr;
__be32 data_size;
__be32 pkt_size;
u8 data[0];
u8 data[];
};
#endif

View File

@ -587,7 +587,7 @@ struct nfp_flower_cmsg_mac_repr {
u8 info;
u8 nbi_port;
u8 phys_port;
} ports[0];
} ports[];
};
#define NFP_FLOWER_CMSG_MAC_REPR_NBI GENMASK(1, 0)
@ -619,7 +619,7 @@ struct nfp_flower_cmsg_merge_hint {
struct {
__be32 host_ctx;
__be64 host_cookie;
} __packed flow[0];
} __packed flow[];
};
enum nfp_flower_cmsg_port_type {

View File

@ -42,7 +42,7 @@ struct nfp_shared_buf;
*/
struct nfp_dumpspec {
u32 size;
u8 data[0];
u8 data[];
};
/**

View File

@ -36,7 +36,7 @@ enum nfp_dumpspec_type {
struct nfp_dump_tl {
__be32 type;
__be32 length; /* chunk length to follow, aligned to 8 bytes */
char data[0];
char data[];
};
/* NFP CPP parameters */
@ -62,7 +62,7 @@ struct nfp_dumpspec_csr {
struct nfp_dumpspec_rtsym {
struct nfp_dump_tl tl;
char rtsym[0];
char rtsym[];
};
/* header for register dumpable */
@ -79,7 +79,7 @@ struct nfp_dump_rtsym {
struct nfp_dump_common_cpp cpp;
__be32 error; /* error code encountered while reading */
u8 padded_name_length; /* pad so data starts at 8 byte boundary */
char rtsym[0];
char rtsym[];
/* after padded_name_length, there is dump_length data */
};
@ -92,7 +92,7 @@ struct nfp_dump_error {
struct nfp_dump_tl tl;
__be32 error;
char padding[4];
char spec[0];
char spec[];
};
/* to track state through debug size calculation TLV traversal */

View File

@ -18,7 +18,7 @@ struct nfp_port;
*/
struct nfp_reprs {
unsigned int num_reprs;
struct net_device __rcu *reprs[0];
struct net_device __rcu *reprs[];
};
/**

View File

@ -183,7 +183,7 @@ struct nfp_eth_table {
bool is_split;
unsigned int fec_modes_supported;
} ports[0];
} ports[];
};
struct nfp_eth_table *nfp_eth_read_ports(struct nfp_cpp *cpp);