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")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200220132017.GA29262@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
unsigned char *cell_buf; /* holds partial rx cell */
unsigned int buf_usage;
- struct urb *urbs[0];
+ struct urb *urbs[];
};
static inline void *to_usbatm_driver_data(struct usb_interface *intf)
u32 flags;
u16 interval;
struct dwc2_hcd_pipe_info pipe_info;
- struct dwc2_hcd_iso_packet_desc iso_descs[0];
+ struct dwc2_hcd_iso_packet_desc iso_descs[];
};
/* Phases for control transfers */
struct dma_aligned_buffer {
void *kmalloc_ptr;
void *old_xfer_buffer;
- u8 data[0];
+ u8 data[];
};
static void free_dma_aligned_buffer(struct urb *urb)
struct list_head tt_list;
/* platform-specific data -- must come last */
- unsigned long priv[0] __aligned(sizeof(s64));
+ unsigned long priv[] __aligned(sizeof(s64));
};
/* convert between an HCD pointer and the corresponding EHCI_HCD */
struct list_head td_list;
unsigned span;
unsigned first_packet;
- struct ehci_iso_packet packet[0];
+ struct ehci_iso_packet packet[];
};
/*
struct fotg210_iso_sched {
struct list_head td_list;
unsigned span;
- struct fotg210_iso_packet packet[0];
+ struct fotg210_iso_packet packet[];
};
/*
u16 length; // # tds in this request
u16 td_cnt; // tds already serviced
struct list_head pending;
- struct td *td [0]; // all TDs in this request
+ struct td *td[]; // all TDs in this request
} urb_priv_t;
struct dentry *debug_dir;
/* platform-specific data -- must come last */
- unsigned long priv[0] __aligned(sizeof(s64));
+ unsigned long priv[] __aligned(sizeof(s64));
};
u32 pkts;
u32 cs_count;
u32 burst_mode;
- u32 bw_budget_table[0];
+ u32 bw_budget_table[];
};
#define MU3C_U3_PORT_MAX 4
struct urb_priv {
int num_tds;
int num_tds_done;
- struct xhci_td td[0];
+ struct xhci_td td[];
};
/*
void *dbc;
/* platform-specific data -- must come last */
- unsigned long priv[0] __aligned(sizeof(s64));
+ unsigned long priv[] __aligned(sizeof(s64));
};
/* Platform specific overrides to generic XHCI hc_driver ops */
__u8 Type; // Type of descriptor
__le16 Size; // Size of data only not including header
__u8 CheckSum; // Checksum (8 bit sum of data only)
- __u8 Data[0]; // Data starts here
+ __u8 Data[]; // Data starts here
} __attribute__((packed));
// for 5152 devices only (type 2 record)
struct ti_i2c_firmware_rec {
__u8 Ver_Major; // Firmware Major version number
__u8 Ver_Minor; // Firmware Minor version number
- __u8 Data[0]; // Download starts here
+ __u8 Data[]; // Download starts here
} __attribute__((packed));
u8 bDataCounter;
__be16 wBaseAddrHi;
__be16 wBaseAddrLo;
- u8 bData[0];
+ u8 bData[];
} __packed;
struct ti_read_data_request {
__u8 bCmdCode;
__u8 bModuleId;
__u8 bErrorCode;
- __u8 bData[0];
+ __u8 bData[];
} __packed;
/* Interrupt struct */
/* variable-length array of alternate settings for this interface,
* stored in no particular order */
- struct usb_host_interface altsetting[0];
+ struct usb_host_interface altsetting[];
};
#define ref_to_usb_interface_cache(r) \
container_of(r, struct usb_interface_cache, ref)
int error_count; /* (return) number of ISO errors */
void *context; /* (in) context for completion */
usb_complete_t complete; /* (in) completion routine */
- struct usb_iso_packet_descriptor iso_frame_desc[0];
+ struct usb_iso_packet_descriptor iso_frame_desc[];
/* (in) ISO ONLY */
};
__u8 bSourceID;
/* bmaControls is actually u32,
* but u8 is needed for the hybrid parser */
- __u8 bmaControls[0]; /* variable length */
+ __u8 bmaControls[]; /* variable length */
} __attribute__((packed));
/* 4.9.2 Class-Specific AS Interface Descriptor */
__u8 bSourceID;
/* bmaControls is actually u32,
* but u8 is needed for the hybrid parser */
- __u8 bmaControls[0]; /* variable length */
+ __u8 bmaControls[]; /* variable length */
/* wFeatureDescrStr omitted */
} __attribute__((packed));
struct usb_gadget_string_container {
struct list_head list;
- u8 *stash[0];
+ u8 *stash[];
};
/* put descriptor for string with that id into buf (buflen >= 256) */
/* The HC driver's private data is stored at the end of
* this structure.
*/
- unsigned long hcd_priv[0]
+ unsigned long hcd_priv[]
__attribute__ ((aligned(sizeof(s64))));
};
compat_int_t error_count;
compat_uint_t signr;
compat_caddr_t usercontext; /* unused */
- struct usbdevfs_iso_packet_desc iso_frame_desc[0];
+ struct usbdevfs_iso_packet_desc iso_frame_desc[];
};
struct usbdevfs_ioctl32 {
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