[PATCH 1/3] xfs: annotate struct xfs_attr_list_context with __counted_by_ptr

[Andrey Albershteyn <aalbersh@kernel.org>]

From: Bill Wendling <morbo@google.com>

Source kernel commit: e5966096d0856d071269cb5928d6bc33342d2dfd

Add the `__counted_by_ptr` attribute to the `buffer` field of `struct
xfs_attr_list_context`. This field is used to point to a buffer of
size `bufsize`.

The `buffer` field is assigned in:
1. `xfs_ioc_attr_list` in `fs/xfs/xfs_handle.c`
2. `xfs_xattr_list` in `fs/xfs/xfs_xattr.c`
3. `xfs_getparents` in `fs/xfs/xfs_handle.c` (implicitly initialized to NULL)

In `xfs_ioc_attr_list`, `buffer` was assigned before `bufsize`. Reorder
them to ensure `bufsize` is set before `buffer` is assigned, although
no access happens between them.

In `xfs_xattr_list`, `buffer` was assigned before `bufsize`. Reorder
them to ensure `bufsize` is set before `buffer` is assigned.

In `xfs_getparents`, `buffer` is NULL (from zero initialization) and
remains NULL. `bufsize` is set to a non-zero value, but since `buffer`
is NULL, no access occurs.

In all cases, the pointer `buffer` is not accessed before `bufsize` is set.

This patch was generated by CodeMender and reviewed by Bill Wendling.
Tested by running xfstests.

Signed-off-by: Bill Wendling <morbo@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
---
 include/platform_defs.h | 3 +++
 libxfs/xfs_attr.h       | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/platform_defs.h b/include/platform_defs.h
index b2d80597a83a..5a829db66e08 100644
--- a/include/platform_defs.h
+++ b/include/platform_defs.h
@@ -330,4 +330,7 @@ struct kvec {
 #define BLK_ZONE_COND_ACTIVE	0xff
 #endif
 
+/* xfs_attr.h */
+#define __counted_by_ptr(member)
+
 #endif	/* __XFS_PLATFORM_DEFS_H__ */
diff --git a/libxfs/xfs_attr.h b/libxfs/xfs_attr.h
index 8244305949de..67fd9c75ac3f 100644
--- a/libxfs/xfs_attr.h
+++ b/libxfs/xfs_attr.h
@@ -55,7 +55,8 @@ struct xfs_attr_list_context {
 	struct xfs_trans	*tp;
 	struct xfs_inode	*dp;		/* inode */
 	struct xfs_attrlist_cursor_kern cursor;	/* position in list */
-	void			*buffer;	/* output buffer */
+	/* output buffer */
+	void			*buffer __counted_by_ptr(bufsize);
 
 	/*
 	 * Abort attribute list iteration if non-zero.  Can be used to pass
-- 
2.51.2