[PATCH] fat: Fix potential shift wrap with FITRIM ioctl on FAT

[PATCH] fat: Fix potential shift wrap with FITRIM ioctl on FAT

[OGAWA Hirofumi]

This patch is the fix of fat-add-fitrim-ioctl-for-fat-file-system.patch.
Maybe better to merge with it (if it is easy).

Anyway, please apply this with above patch.

--------
From: Wentao Wang <witallwang@gmail.com>

If we keep "trimmed" as an u32, there will be a potential shift wrap.

It would be a problem on a larger than 4GB partition with
FAT32. Though most tools who call this ioctl would ignore this value,
it would be great to fix it.

Signed-off-by: Wentao Wang <witallwang@gmail.com>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---

 fs/fat/fatent.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN fs/fat/fatent.c~fat-fitrim-fix fs/fat/fatent.c
--- linux/fs/fat/fatent.c~fat-fitrim-fix	2018-07-13 15:39:14.417110998 +0900
+++ linux-hirofumi/fs/fat/fatent.c	2018-07-13 15:39:14.418110996 +0900
@@ -705,8 +705,8 @@ int fat_trim_fs(struct inode *inode, str
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 	const struct fatent_operations *ops = sbi->fatent_ops;
 	struct fat_entry fatent;
-	u64 ent_start, ent_end, minlen;
-	u32 free = 0, trimmed = 0;
+	u64 ent_start, ent_end, minlen, trimmed = 0;
+	u32 free = 0;
 	unsigned long reada_blocks, reada_mask, cur_block = 0;
 	int err = 0;
 
_

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>