Merge tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

Pull flexible-array member conversions from Gustavo A. R. Silva:
 "Replace zero-length arrays with flexible-array members.

  Notice that all of these patches have been baking in linux-next for
  two development cycles now.

  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].

  C99 introduced “flexible array members”, which lacks a numeric size
  for the array declaration entirely:

        struct something {
                size_t count;
                struct foo items[];
        };

  This is the way the kernel expects dynamically sized trailing elements
  to be declared. It allows the compiler to generate errors when the
  flexible array does not occur last in the structure, which helps to
  prevent some kind of undefined behavior[3] bugs from being
  inadvertently introduced to the codebase.

  It also allows the compiler to correctly analyze array sizes (via
  sizeof(), CONFIG_FORTIFY_SOURCE, and CONFIG_UBSAN_BOUNDS). For
  instance, there is no mechanism that warns us that the following
  application of the sizeof() operator to a zero-length array always
  results in zero:

        struct something {
                size_t count;
                struct foo items[0];
        };

        struct something *instance;

        instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
        instance->count = count;

        size = sizeof(instance->items) * instance->count;
        memcpy(instance->items, source, size);

  At the last line of code above, size turns out to be zero, when one
  might have thought it represents the total size in bytes of the
  dynamic memory recently allocated for the trailing array items. Here
  are a couple examples of this issue[4][5].

  Instead, flexible array members have incomplete type, and so the
  sizeof() operator may not be applied[6], so any misuse of such
  operators will be immediately noticed at build time.

  The cleanest and least error-prone way to implement this is through
  the use of a flexible array member:

        struct something {
                size_t count;
                struct foo items[];
        };

        struct something *instance;

        instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
        instance->count = count;

        size = sizeof(instance->items[0]) * instance->count;
        memcpy(instance->items, source, size);

  instead"

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
[4] commit f2cd32a443da ("rndis_wlan: Remove logically dead code")
[5] commit ab91c2a89f86 ("tpm: eventlog: Replace zero-length array with flexible-array member")
[6] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html

* tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (41 commits)
  w1: Replace zero-length array with flexible-array
  tracing/probe: Replace zero-length array with flexible-array
  soc: ti: Replace zero-length array with flexible-array
  tifm: Replace zero-length array with flexible-array
  dmaengine: tegra-apb: Replace zero-length array with flexible-array
  stm class: Replace zero-length array with flexible-array
  Squashfs: Replace zero-length array with flexible-array
  ASoC: SOF: Replace zero-length array with flexible-array
  ima: Replace zero-length array with flexible-array
  sctp: Replace zero-length array with flexible-array
  phy: samsung: Replace zero-length array with flexible-array
  RxRPC: Replace zero-length array with flexible-array
  rapidio: Replace zero-length array with flexible-array
  media: pwc: Replace zero-length array with flexible-array
  firmware: pcdp: Replace zero-length array with flexible-array
  oprofile: Replace zero-length array with flexible-array
  block: Replace zero-length array with flexible-array
  tools/testing/nvdimm: Replace zero-length array with flexible-array
  libata: Replace zero-length array with flexible-array
  kprobes: Replace zero-length array with flexible-array
  ...

4 files changed, 12 insertions, 12 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 7ecddc2f38db..91e7cc4a9f17 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -67,7 +67,7 @@ struct aio_ring {
 	unsigned	header_length;	/* size of aio_ring */
 
 
-	struct io_event		io_events[0];
+	struct io_event		io_events[];
 }; /* 128 bytes + ring size */
 
 /*
diff --git a/fs/jffs2/nodelist.h b/fs/jffs2/nodelist.h
index 0637271f3770..8ff4d1a1e774 100644
--- a/fs/jffs2/nodelist.h
+++ b/fs/jffs2/nodelist.h
@@ -259,7 +259,7 @@ struct jffs2_full_dirent
 	uint32_t ino; /* == zero for unlink */
 	unsigned int nhash;
 	unsigned char type;
-	unsigned char name[0];
+	unsigned char name[];
 };
 
 /*
diff --git a/fs/jffs2/summary.h b/fs/jffs2/summary.h
index 60207a2ae952..e4131cb1f1d4 100644
--- a/fs/jffs2/summary.h
+++ b/fs/jffs2/summary.h
@@ -61,7 +61,7 @@ struct jffs2_sum_dirent_flash
 	jint32_t ino; 		/* == zero for unlink */
 	uint8_t nsize;		/* dirent name size */
 	uint8_t type;		/* dirent type */
-	uint8_t name[0];	/* dirent name */
+	uint8_t name[];	/* dirent name */
 } __attribute__((packed));
 
 struct jffs2_sum_xattr_flash
@@ -117,7 +117,7 @@ struct jffs2_sum_dirent_mem
 	jint32_t ino; 		/* == zero for unlink */
 	uint8_t nsize;		/* dirent name size */
 	uint8_t type;		/* dirent type */
-	uint8_t name[0];	/* dirent name */
+	uint8_t name[];	/* dirent name */
 } __attribute__((packed));
 
 struct jffs2_sum_xattr_mem
diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index 7187bd1a30ea..8d64edb80ebf 100644
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -262,7 +262,7 @@ struct squashfs_dir_index {
 	__le32			index;
 	__le32			start_block;
 	__le32			size;
-	unsigned char		name[0];
+	unsigned char		name[];
 };
 
 struct squashfs_base_inode {
@@ -327,7 +327,7 @@ struct squashfs_symlink_inode {
 	__le32			inode_number;
 	__le32			nlink;
 	__le32			symlink_size;
-	char			symlink[0];
+	char			symlink[];
 };
 
 struct squashfs_reg_inode {
@@ -341,7 +341,7 @@ struct squashfs_reg_inode {
 	__le32			fragment;
 	__le32			offset;
 	__le32			file_size;
-	__le16			block_list[0];
+	__le16			block_list[];
 };
 
 struct squashfs_lreg_inode {
@@ -358,7 +358,7 @@ struct squashfs_lreg_inode {
 	__le32			fragment;
 	__le32			offset;
 	__le32			xattr;
-	__le16			block_list[0];
+	__le16			block_list[];
 };
 
 struct squashfs_dir_inode {
@@ -389,7 +389,7 @@ struct squashfs_ldir_inode {
 	__le16			i_count;
 	__le16			offset;
 	__le32			xattr;
-	struct squashfs_dir_index	index[0];
+	struct squashfs_dir_index	index[];
 };
 
 union squashfs_inode {
@@ -410,7 +410,7 @@ struct squashfs_dir_entry {
 	__le16			inode_number;
 	__le16			type;
 	__le16			size;
-	char			name[0];
+	char			name[];
 };
 
 struct squashfs_dir_header {
@@ -428,12 +428,12 @@ struct squashfs_fragment_entry {
 struct squashfs_xattr_entry {
 	__le16			type;
 	__le16			size;
-	char			data[0];
+	char			data[];
 };
 
 struct squashfs_xattr_val {
 	__le32			vsize;
-	char			value[0];
+	char			value[];
 };
 
 struct squashfs_xattr_id {