linux-kernel - [PATCH 1/2] f2fs: fix to avoid overflow when left shifting page offset

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Date:   Wed, 25 Jan 2017 10:52:39 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>,
        Chao Yu <yuchao0@...wei.com>
Subject: [PATCH 1/2] f2fs: fix to avoid overflow when left shifting page offset

We use following method to calculate size with current page index:
size = index << PAGE_SHIFT
If type of index has only 32-bits size, left shifting will incur overflow,
which makes result incorrect.

So let's cast index with 64-bits type to avoid such issue.

Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
 fs/f2fs/recovery.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index 4fb4471a3206..e93316ea8d1b 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -428,8 +428,9 @@ static int do_recover_data(struct f2fs_sb_info *sbi, struct inode *inode,
 		}
 
 		if (!file_keep_isize(inode) &&
-				(i_size_read(inode) <= (start << PAGE_SHIFT)))
-			f2fs_i_size_write(inode, (start + 1) << PAGE_SHIFT);
+			(i_size_read(inode) <= ((loff_t)start << PAGE_SHIFT)))
+			f2fs_i_size_write(inode,
+				(loff_t)(start + 1) << PAGE_SHIFT);
 
 		/*
 		 * dest is reserved block, invalidate src block
-- 
2.8.2.295.g3f1c1d0