scsi: 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Link: https://lore.kernel.org/r/20200224161406.GA21454@embeddedor
Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Satish Kharat <satishkh@cisco.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

9 files changed, 12 insertions, 12 deletions

diff --git a/drivers/scsi/fnic/vnic_devcmd.h b/drivers/scsi/fnic/vnic_devcmd.h
index c5dde556dc7c..c20d30e36dfc 100644
--- a/drivers/scsi/fnic/vnic_devcmd.h
+++ b/drivers/scsi/fnic/vnic_devcmd.h
@@ -442,7 +442,7 @@ struct vnic_devcmd_notify {
 struct vnic_devcmd_provinfo {
 	u8 oui[3];
 	u8 type;
-	u8 data[0];
+	u8 data[];
 };
 
 /*
diff --git a/drivers/scsi/ipr.h b/drivers/scsi/ipr.h
index a67baeb36d1f..fd3929a19ab5 100644
--- a/drivers/scsi/ipr.h
+++ b/drivers/scsi/ipr.h
@@ -451,12 +451,12 @@ struct ipr_config_table_hdr64 {
 
 struct ipr_config_table {
 	struct ipr_config_table_hdr hdr;
-	struct ipr_config_table_entry dev[0];
+	struct ipr_config_table_entry dev[];
 }__attribute__((packed, aligned (4)));
 
 struct ipr_config_table64 {
 	struct ipr_config_table_hdr64 hdr64;
-	struct ipr_config_table_entry64 dev[0];
+	struct ipr_config_table_entry64 dev[];
 }__attribute__((packed, aligned (8)));
 
 struct ipr_config_table_entry_wrapper {
@@ -792,7 +792,7 @@ struct ipr_mode_page28 {
 	struct ipr_mode_page_hdr hdr;
 	u8 num_entries;
 	u8 entry_length;
-	struct ipr_dev_bus_entry bus[0];
+	struct ipr_dev_bus_entry bus[];
 }__attribute__((packed));
 
 struct ipr_mode_page24 {
diff --git a/drivers/scsi/isci/sas.h b/drivers/scsi/isci/sas.h
index dc26b4aea99e..15d8f3631ab7 100644
--- a/drivers/scsi/isci/sas.h
+++ b/drivers/scsi/isci/sas.h
@@ -201,7 +201,7 @@ struct smp_req {
 	u8 func;		/* byte 1 */
 	u8 alloc_resp_len;	/* byte 2 */
 	u8 req_len;		/* byte 3 */
-	u8 req_data[0];
+	u8 req_data[];
 }  __packed;
 
 /*
diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index c597d544eb39..778d5e6ce385 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -207,7 +207,7 @@ struct fw_event_work {
 	u8			ignore;
 	u16			event;
 	struct kref		refcount;
-	char			event_data[0] __aligned(4);
+	char			event_data[] __aligned(4);
 };
 
 static void fw_event_work_free(struct kref *r)
diff --git a/drivers/scsi/mvsas/mv_sas.h b/drivers/scsi/mvsas/mv_sas.h
index 519edc796691..327fdd5ee962 100644
--- a/drivers/scsi/mvsas/mv_sas.h
+++ b/drivers/scsi/mvsas/mv_sas.h
@@ -394,7 +394,7 @@ struct mvs_info {
 	dma_addr_t bulk_buffer_dma1;
 #define TRASH_BUCKET_SIZE    	0x20000
 	void *dma_pool;
-	struct mvs_slot_info slot_info[0];
+	struct mvs_slot_info slot_info[];
 };
 
 struct mvs_prv_info{
diff --git a/drivers/scsi/mvumi.h b/drivers/scsi/mvumi.h
index ec8cc2207536..60d5691fc4ab 100644
--- a/drivers/scsi/mvumi.h
+++ b/drivers/scsi/mvumi.h
@@ -130,7 +130,7 @@ enum {
 struct mvumi_hotplug_event {
 	u16 size;
 	u8 dummy[2];
-	u8 bitmap[0];
+	u8 bitmap[];
 };
 
 struct mvumi_driver_event {
@@ -290,7 +290,7 @@ struct mvumi_rsp_frame {
 
 struct mvumi_ob_data {
 	struct list_head list;
-	unsigned char data[0];
+	unsigned char data[];
 };
 
 struct version_info {
diff --git a/drivers/scsi/pmcraid.h b/drivers/scsi/pmcraid.h
index a4f7eb8f50a3..15c962108075 100644
--- a/drivers/scsi/pmcraid.h
+++ b/drivers/scsi/pmcraid.h
@@ -623,7 +623,7 @@ struct pmcraid_aen_msg {
 	u32 hostno;
 	u32 length;
 	u8  reserved[8];
-	u8  data[0];
+	u8  data[];
 };
 
 /* Controller state event message type */
diff --git a/drivers/scsi/snic/vnic_devcmd.h b/drivers/scsi/snic/vnic_devcmd.h
index d81b4f0ceaaa..0e0fa38f8d90 100644
--- a/drivers/scsi/snic/vnic_devcmd.h
+++ b/drivers/scsi/snic/vnic_devcmd.h
@@ -208,7 +208,7 @@ struct vnic_devcmd_notify {
 struct vnic_devcmd_provinfo {
 	u8 oui[3];
 	u8 type;
-	u8 data[0];
+	u8 data[];
 };
 
 /*
diff --git a/drivers/scsi/stex.c b/drivers/scsi/stex.c
index 33287b6bdf0e..d4f10c0d813c 100644
--- a/drivers/scsi/stex.c
+++ b/drivers/scsi/stex.c
@@ -236,7 +236,7 @@ struct req_msg {
 	u8 data_dir;
 	u8 payload_sz;		/* payload size in 4-byte, not used */
 	u8 cdb[STEX_CDB_LENGTH];
-	u32 variable[0];
+	u32 variable[];
 };
 
 struct status_msg {