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
76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Link: https://lkml.kernel.org/r/20200221150612.GA9717@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
(waiting for I/O) */
/* per cpu data */
- struct appldata_os_per_cpu os_cpu[0];
+ struct appldata_os_per_cpu os_cpu[];
} __attribute__((packed));
static struct appldata_os_data *appldata_os_data;
struct dasd_diag_req {
unsigned int block_count;
- struct dasd_diag_bio bio[0];
+ struct dasd_diag_bio bio[];
};
static const u8 DASD_DIAG_CMS1[] = { 0xc3, 0xd4, 0xe2, 0xf1 };/* EBCDIC CMS1 */
__u8 imbedded_count;
__u8 extended_operation;
__u16 extended_parameter_length;
- __u8 extended_parameter[0];
+ __u8 extended_parameter[];
} __attribute__ ((packed));
/* Prefix data for format 0x00 and 0x01 */
struct list_head update;
unsigned long size;
unsigned long len;
- char string[0];
+ char string[];
} __attribute__ ((aligned(8)));
static inline struct string *
u8 atype;
u32 fh;
u32 fid;
- u8 data[0];
+ u8 data[];
} __packed;
struct err_notify_sccb {
struct idset {
int num_ssid;
int num_id;
- unsigned long bitmap[0];
+ unsigned long bitmap[];
};
static inline unsigned long bitmap_size(int num_ssid, int num_id)
u8 res1[3];
u32 keytype; /* key type, one of the PKEY_KEYTYPE values */
u32 len; /* bytes actually stored in clearkey[] */
- u8 clearkey[0]; /* clear key value */
+ u8 clearkey[]; /* clear key value */
} __packed;
/*
u16 kmf1; /* key management field 1 */
u16 kmf2; /* key management field 2 */
u16 kmf3; /* key management field 3 */
- u8 vdata[0]; /* variable part data follows */
+ u8 vdata[]; /* variable part data follows */
} __packed;
/* Some defines for the CCA AES cipherkeytoken kmf1 field */
struct CPRBX cprbx;
unsigned char pad[4]; /* 4 byte function code/rules block ? */
unsigned short length;
- char text[0];
+ char text[];
} __packed;
struct type86_ep11_reply {