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

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Message-ID: <87h8l37hub.fsf@mail.parknet.co.jp>
Date:   Fri, 13 Jul 2018 15:47:08 +0900
From:   OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, "Wang\, Matt" <Matt.Wang@...l.com>,
        "dan.carpenter\@oracle.com" <dan.carpenter@...cle.com>
Subject: [PATCH] fat: Fix potential shift wrap with FITRIM ioctl on FAT

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@...il.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@...il.com>
Signed-off-by: OGAWA Hirofumi <hirofumi@...l.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@...l.parknet.co.jp>