From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>
Cc: linux-f2fs-devel@lists.sourceforge.net,
linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-hardening@vger.kernel.org
Subject: [PATCH][next] f2fs: Replace one-element array with flexible-array member
Date: Wed, 24 Feb 2021 13:03:13 -0600 [thread overview]
Message-ID: <20210224190313.GA144040@embeddedor> (raw)
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].
Refactor the code according to the use of a flexible-array member in
struct f2fs_checkpoint, instead of a one-element arrays.
Notice that a temporary pointer to void '*tmp_ptr' was used in order to
fix the following errors when using a flexible array instead of a one
element array in struct f2fs_checkpoint:
CC [M] fs/f2fs/dir.o
In file included from fs/f2fs/dir.c:13:
fs/f2fs/f2fs.h: In function ‘__bitmap_ptr’:
fs/f2fs/f2fs.h:2227:40: error: invalid use of flexible array member
2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
| ^
fs/f2fs/f2fs.h:2227:49: error: invalid use of flexible array member
2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
| ^
fs/f2fs/f2fs.h:2238:40: error: invalid use of flexible array member
2238 | return &ckpt->sit_nat_version_bitmap + offset;
| ^
make[2]: *** [scripts/Makefile.build:287: fs/f2fs/dir.o] Error 1
make[1]: *** [scripts/Makefile.build:530: fs/f2fs] Error 2
make: *** [Makefile:1819: fs] Error 2
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
Link: https://github.com/KSPP/linux/issues/79
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/603647e4.DeEFbl4eqljuwAUe%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
fs/f2fs/f2fs.h | 5 +++--
include/linux/f2fs_fs.h | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e2d302ae3a46..3f5cb097c30f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2215,6 +2215,7 @@ static inline block_t __cp_payload(struct f2fs_sb_info *sbi)
static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
{
struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+ void *tmp_ptr = &ckpt->sit_nat_version_bitmap;
int offset;
if (is_set_ckpt_flags(sbi, CP_LARGE_NAT_BITMAP_FLAG)) {
@@ -2224,7 +2225,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
* if large_nat_bitmap feature is enabled, leave checksum
* protection for all nat/sit bitmaps.
*/
- return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
+ return tmp_ptr + offset + sizeof(__le32);
}
if (__cp_payload(sbi) > 0) {
@@ -2235,7 +2236,7 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
} else {
offset = (flag == NAT_BITMAP) ?
le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
- return &ckpt->sit_nat_version_bitmap + offset;
+ return tmp_ptr + offset;
}
}
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index c6cc0a566ef5..5487a80617a3 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -168,7 +168,7 @@ struct f2fs_checkpoint {
unsigned char alloc_type[MAX_ACTIVE_LOGS];
/* SIT and NAT version bitmap */
- unsigned char sit_nat_version_bitmap[1];
+ unsigned char sit_nat_version_bitmap[];
} __packed;
#define CP_CHKSUM_OFFSET 4092 /* default chksum offset in checkpoint */
--
2.27.0
next reply other threads:[~2021-02-24 19:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-24 19:03 Gustavo A. R. Silva [this message]
2021-02-25 1:37 ` [f2fs-dev] [PATCH][next] f2fs: Replace one-element array with flexible-array member Chao Yu
2021-02-28 5:00 ` Jaegeuk Kim
2021-03-01 3:17 ` Chao Yu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210224190313.GA144040@embeddedor \
--to=gustavoars@kernel.org \
--cc=chao@kernel.org \
--cc=jaegeuk@kernel.org \
--cc=linux-f2fs-devel@lists.sourceforge.net \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).