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
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
fs/ocfs2/ocfs2_fs.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index 638d875eccc7..7aebdbf5cc0a 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -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
--
2.34.1
On Sat, Sep 03, 2022 at 12:59:36AM +0100, Gustavo A. R. Silva wrote:
> 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
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On 9/3/22 7:59 AM, Gustavo A. R. Silva wrote:
> 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
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
Looks good.
Reviewed-by: Joseph Qi <[email protected]>