[PATCH][next] hpfs: Replace one-element array with flexible-array member

From: Gustavo A. R. Silva
Date: Fri Mar 26 2021 - 14:36:03 EST


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].

Also, this helps with the ongoing efforts to enable -Warray-bounds by
fixing the following warning:

CC [M] fs/hpfs/dir.o
fs/hpfs/dir.c: In function ‘hpfs_readdir’:
fs/hpfs/dir.c:163:41: warning: array subscript 1 is above array bounds of ‘u8[1]’ {aka ‘unsigned char[1]’} [-Warray-bounds]
163 | || de ->name[0] != 1 || de->name[1] != 1))
| ~~~~~~~~^~~

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
---
fs/hpfs/hpfs.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/hpfs/hpfs.h b/fs/hpfs/hpfs.h
index 302f45101a96..d92c4af3e1b4 100644
--- a/fs/hpfs/hpfs.h
+++ b/fs/hpfs/hpfs.h
@@ -356,7 +356,8 @@ struct hpfs_dirent {
u8 no_of_acls; /* number of ACL's (low 3 bits) */
u8 ix; /* code page index (of filename), see
struct code_page_data */
- u8 namelen, name[1]; /* file name */
+ u8 namelen; /* file name length */
+ u8 name[]; /* file name */
/* dnode_secno down; btree down pointer, if present,
follows name on next word boundary, or maybe it
precedes next dirent, which is on a word boundary. */
--
2.27.0