Commit 6e4a53ee authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by Andrew Morton
Browse files

ocfs2: replace zero-length arrays with DECLARE_FLEX_ARRAY() helper 

Zero-length arrays are deprecated and we are moving towards adopting C99
flexible-array members, instead.  So, replace zero-length array
declarations in a couple of structures and unions with the new
DECLARE_FLEX_ARRAY() helper macro.

This helper allows for a flexible-array member in a union and as only
member in a structure.

Also, this addresses multiple warnings reported when building with
Clang-15 and -Wzero-length-array.

Lastly, this will also help memcpy (in a coming hardening update) execute
proper bounds-checking on variable length object i_symlink at
fs/ocfs2/namei.c:1973:

fs/ocfs2/namei.c:
1973                 memcpy((char *) fe->id2.i_symlink, symname, l);

Link: https://github.com/KSPP/linux/issues/21
Link: https://github.com/KSPP/linux/issues/193
Link: https://github.com/KSPP/linux/issues/197
Link: https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
Link: https://lkml.kernel.org/r/YxKY6O2hmdwNh8r8@work


Signed-off-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b8147511

fs/ocfs2/ocfs2_fs.h

+4 −4
Original line number Diff line number Diff line
@@ -527,7 +527,7 @@ struct ocfs2_extent_block 
 * value -1 (0xFFFF) is OCFS2_INVALID_SLOT.  This marks a slot empty.

 */

struct ocfs2_slot_map {

/*00*/	__le16 sm_slots[0];

/*00*/	DECLARE_FLEX_ARRAY(__le16, sm_slots);

/*

 * Actual on-disk size is one block.  OCFS2_MAX_SLOTS is 255,

 * 255 * sizeof(__le16) == 512B, within the 512B block minimum blocksize.
@@ -548,7 +548,7 @@ struct ocfs2_extended_slot { 
 * i_size.

 */

struct ocfs2_slot_map_extended {

/*00*/	struct ocfs2_extended_slot se_slots[0];

/*00*/	DECLARE_FLEX_ARRAY(struct ocfs2_extended_slot, se_slots);

/*

 * Actual size is i_size of the slot_map system file.  It should

 * match s_max_slots * sizeof(struct ocfs2_extended_slot)
@@ -727,7 +727,7 @@ struct ocfs2_dinode { 
		struct ocfs2_extent_list	i_list;

		struct ocfs2_truncate_log	i_dealloc;

		struct ocfs2_inline_data	i_data;

		__u8               		i_symlink[0];

		DECLARE_FLEX_ARRAY(__u8,	i_symlink);

	} id2;

/* Actual on-disk size is one block */

};
@@ -892,7 +892,7 @@ struct ocfs2_group_desc 
/*30*/	struct ocfs2_block_check bg_check;	/* Error checking */

	__le64   bg_reserved2;

/*40*/	union {

		__u8    bg_bitmap[0];

		DECLARE_FLEX_ARRAY(__u8, bg_bitmap);

		struct {

			/*

			 * Block groups may be discontiguous when