treewide: uapi: Replace zero-length arrays with flexible-array members

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

This code was transformed with the help of Coccinelle:
(linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

@@
identifier S, member, array;
type T1, T2;
@@

struct S {
  ...
  T1 member;
  T2 array[
- 0
  ];
};

-fstrict-flex-arrays=3 is coming and we need to land these changes
to prevent issues like these in the short future:

../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0,
but the source string has length 2 (including NUL byte) [-Wfortify-source]
		strcpy(de3->name, ".");
		^

Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If
this breaks anything, we can use a union with a new member name.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/62b675ec.wKX6AOZ6cbE71vtF%25lkp@intel.com/
Acked-by: Dan Williams <dan.j.williams@intel.com> # For ndctl.h
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

2 files changed, 10 insertions, 10 deletions

diff --git a/include/uapi/scsi/fc/fc_els.h b/include/uapi/scsi/fc/fc_els.h
index c9812c5c2fc4..16782c360de3 100644
--- a/include/uapi/scsi/fc/fc_els.h
+++ b/include/uapi/scsi/fc/fc_els.h
@@ -264,7 +264,7 @@ struct fc_tlv_desc {
 					 * Size of descriptor excluding
 					 * desc_tag and desc_len fields.
 					 */
-	__u8		desc_value[0];  /* Descriptor Value */
+	__u8		desc_value[];  /* Descriptor Value */
 };
 
 /* Descriptor tag and len fields are considered the mandatory header
@@ -1027,7 +1027,7 @@ struct fc_fn_li_desc {
 					 * threshold to caause the LI event
 					 */
 	__be32		pname_count;	/* number of portname_list elements */
-	__be64		pname_list[0];	/* list of N_Port_Names accessible
+	__be64		pname_list[];	/* list of N_Port_Names accessible
 					 * through the attached port
 					 */
 };
@@ -1069,7 +1069,7 @@ struct fc_fn_peer_congn_desc {
 					 * congestion event
 					 */
 	__be32		pname_count;	/* number of portname_list elements */
-	__be64		pname_list[0];	/* list of N_Port_Names accessible
+	__be64		pname_list[];	/* list of N_Port_Names accessible
 					 * through the attached port
 					 */
 };
@@ -1104,7 +1104,7 @@ struct fc_els_fpin {
 					 * Size of ELS excluding fpin_cmd,
 					 * fpin_zero and desc_len fields.
 					 */
-	struct fc_tlv_desc	fpin_desc[0];	/* Descriptor list */
+	struct fc_tlv_desc	fpin_desc[];	/* Descriptor list */
 };
 
 /* Diagnostic Function Descriptor - FPIN Registration */
@@ -1115,7 +1115,7 @@ struct fc_df_desc_fpin_reg {
 					 * desc_tag and desc_len fields.
 					 */
 	__be32		count;		/* Number of desc_tags elements */
-	__be32		desc_tags[0];	/* Array of Descriptor Tags.
+	__be32		desc_tags[];	/* Array of Descriptor Tags.
 					 * Each tag indicates a function
 					 * supported by the N_Port (request)
 					 * or by the  N_Port and Fabric
@@ -1135,7 +1135,7 @@ struct fc_els_rdf {
 					 * Size of ELS excluding fpin_cmd,
 					 * fpin_zero and desc_len fields.
 					 */
-	struct fc_tlv_desc	desc[0];	/* Descriptor list */
+	struct fc_tlv_desc	desc[];	/* Descriptor list */
 };
 
 /*
@@ -1148,7 +1148,7 @@ struct fc_els_rdf_resp {
 						 * and desc_list_len fields.
 						 */
 	struct fc_els_lsri_desc	lsri;
-	struct fc_tlv_desc	desc[0];	/* Supported Descriptor list */
+	struct fc_tlv_desc	desc[];	/* Supported Descriptor list */
 };
 
 
@@ -1231,7 +1231,7 @@ struct fc_els_edc {
 					 * Size of ELS excluding edc_cmd,
 					 * edc_zero and desc_len fields.
 					 */
-	struct fc_tlv_desc	desc[0];
+	struct fc_tlv_desc	desc[];
 					/* Diagnostic Descriptor list */
 };
 
@@ -1245,7 +1245,7 @@ struct fc_els_edc_resp {
 						 * and desc_list_len fields.
 						 */
 	struct fc_els_lsri_desc	lsri;
-	struct fc_tlv_desc	desc[0];
+	struct fc_tlv_desc	desc[];
 				    /* Supported Diagnostic Descriptor list */
 };
 
diff --git a/include/uapi/scsi/scsi_bsg_fc.h b/include/uapi/scsi/scsi_bsg_fc.h
index 3ae65e93235c..7f5930801f72 100644
--- a/include/uapi/scsi/scsi_bsg_fc.h
+++ b/include/uapi/scsi/scsi_bsg_fc.h
@@ -209,7 +209,7 @@ struct fc_bsg_host_vendor {
 	__u64 vendor_id;
 
 	/* start of vendor command area */
-	__u32 vendor_cmd[0];
+	__u32 vendor_cmd[];
 };
 
 /* Response: