Commit 3f6e9633 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by David S. Miller
Browse files

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 76497732 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: default avatarGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f49b2759

drivers/net/ethernet/netronome/nfp/bpf/fw.h

+3 −3
Original line number Diff line number Diff line
@@ -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

drivers/net/ethernet/netronome/nfp/flower/cmsg.h

+2 −2
Original line number Diff line number Diff line
@@ -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 {

drivers/net/ethernet/netronome/nfp/nfp_main.h

+1 −1
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ struct nfp_shared_buf; 
 */

struct nfp_dumpspec {

	u32 size;

	u8 data[0];

	u8 data[];

};



/**

drivers/net/ethernet/netronome/nfp/nfp_net_debugdump.c

+4 −4
Original line number Diff line number Diff line
@@ -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 */

drivers/net/ethernet/netronome/nfp/nfp_net_repr.h

+1 −1
Original line number Diff line number Diff line
@@ -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[];

};



/**

CRA Git | Maintained and supported by SUSTech CRA and CCSE