Commit f49b2759 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by David S. Miller
Browse files

toshiba: 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 65dc2f1a

drivers/net/ethernet/toshiba/ps3_gelic_net.h

+1 −1
Original line number Diff line number Diff line
@@ -308,7 +308,7 @@ struct gelic_port { 
	struct gelic_card *card;

	struct net_device *netdev;

	enum gelic_port_type type;

	long priv[0]; /* long for alignment */

	long priv[]; /* long for alignment */

};



static inline struct gelic_card *port_to_card(struct gelic_port *p)

drivers/net/ethernet/toshiba/ps3_gelic_wireless.h

+1 −1
Original line number Diff line number Diff line
@@ -158,7 +158,7 @@ struct gelic_eurus_scan_info { 
	__be32 reserved2;

	__be32 reserved3;

	__be32 reserved4;

	u8 elements[0]; /* ie */

	u8 elements[]; /* ie */

} __packed;



/* the hypervisor returns bbs up to 16 */

drivers/net/ethernet/toshiba/spider_net.h

+1 −1
Original line number Diff line number Diff line
@@ -470,7 +470,7 @@ struct spider_net_card { 
	struct spider_net_extra_stats spider_stats;



	/* Must be last item in struct */

	struct spider_net_descr darray[0];

	struct spider_net_descr darray[];

};



#endif

drivers/net/ethernet/toshiba/tc35815.c

+1 −1
Original line number Diff line number Diff line
@@ -367,7 +367,7 @@ struct TxFD { 


struct RxFD {

	struct FDesc fd;

	struct BDesc bd[0];	/* variable length */

	struct BDesc bd[];	/* variable length */

};



struct FrFD {