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toshiba: Replace zero-length array with flexible-array member

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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 10:32:52 -06:00 committed by David S. Miller
parent 65dc2f1a44
commit f49b275982
4 changed files with 4 additions and 4 deletions
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2
drivers/net/ethernet/toshiba/ps3_gelic_net.h
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@ -308,7 +308,7 @@ struct gelic_port {
struct gelic_card *card; struct gelic_card *card;
struct net_device *netdev; struct net_device *netdev;
enum gelic_port_type type; 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) static inline struct gelic_card *port_to_card(struct gelic_port *p)

2
drivers/net/ethernet/toshiba/ps3_gelic_wireless.h
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@ -158,7 +158,7 @@ struct gelic_eurus_scan_info {
__be32 reserved2; __be32 reserved2;
__be32 reserved3; __be32 reserved3;
__be32 reserved4; __be32 reserved4;
u8 elements[0]; /* ie */ u8 elements[]; /* ie */
} __packed; } __packed;
/* the hypervisor returns bbs up to 16 */ /* the hypervisor returns bbs up to 16 */

2
drivers/net/ethernet/toshiba/spider_net.h
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@ -470,7 +470,7 @@ struct spider_net_card {
struct spider_net_extra_stats spider_stats; struct spider_net_extra_stats spider_stats;
/* Must be last item in struct */ /* Must be last item in struct */
struct spider_net_descr darray[0]; struct spider_net_descr darray[];
}; };
#endif #endif

2
drivers/net/ethernet/toshiba/tc35815.c
View File

@ -367,7 +367,7 @@ struct TxFD {
struct RxFD { struct RxFD {
struct FDesc fd; struct FDesc fd;
struct BDesc bd[0]; /* variable length */ struct BDesc bd[]; /* variable length */
}; };
struct FrFD { struct FrFD {