[PATCH] f2fs: avoid format-overflow warning

[PATCH] f2fs: avoid format-overflow warning

[Su Hui]

With gcc and W=1 option, there's a warning like this:

fs/f2fs/compress.c: In function ‘f2fs_init_page_array_cache’:
fs/f2fs/compress.c:1984:47: error: ‘%u’ directive writing between
1 and 7 bytes into a region of size between 5 and 8
[-Werror=format-overflow=]
 1984 |  sprintf(slab_name, "f2fs_page_array_entry-%u:%u", MAJOR(dev),
		MINOR(dev));
      |                                               ^~

String "f2fs_page_array_entry-%u:%u" can up to 35. The first "%u" can up
to 4 and the second "%u" can up to 7, so total size is "24 + 4 + 7 = 35".
slab_name's size should be 35 rather than 32.

Signed-off-by: Su Hui <suhui@nfschina.com>
---
 fs/f2fs/compress.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index d820801f473e..7514661bbfbb 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1976,7 +1976,7 @@ void f2fs_destroy_compress_inode(struct f2fs_sb_info *sbi)
 int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi)
 {
 	dev_t dev = sbi->sb->s_bdev->bd_dev;
-	char slab_name[32];
+	char slab_name[35];
 
 	if (!f2fs_sb_has_compression(sbi))
 		return 0;
-- 
2.30.2

Re: [PATCH] f2fs: avoid format-overflow warning

[Chao Yu]

On 2023/10/8 14:39, Su Hui wrote:
> With gcc and W=1 option, there's a warning like this:
> 
> fs/f2fs/compress.c: In function ‘f2fs_init_page_array_cache’:
> fs/f2fs/compress.c:1984:47: error: ‘%u’ directive writing between
> 1 and 7 bytes into a region of size between 5 and 8
> [-Werror=format-overflow=]
>   1984 |  sprintf(slab_name, "f2fs_page_array_entry-%u:%u", MAJOR(dev),
> 		MINOR(dev));
>        |                                               ^~
> 
> String "f2fs_page_array_entry-%u:%u" can up to 35. The first "%u" can up
> to 4 and the second "%u" can up to 7, so total size is "24 + 4 + 7 = 35".
> slab_name's size should be 35 rather than 32.
> 
> Signed-off-by: Su Hui <suhui@nfschina.com>

Looks good to me, thanks for the patch.

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,