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Subject: Re: [PATCH] squashfs: fix mtime underflow on 64 bit system
To:     <phillip@squashfs.org.uk>, <linux-kernel@vger.kernel.org>
CC:     <houtao1@huawei.com>, <zhaohongjiang@huawei.com>
References: <20190117082148.129347-1-zhengbin13@huawei.com>
From:   "zhengbin (A)" <zhengbin13@huawei.com>
Message-ID: <8b7bd95a-ff67-6e8d-8dc0-6a758e25c811@huawei.com>
Date:   Wed, 23 Jan 2019 17:00:23 +0800
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On 2019/1/17 16:21, zhengbin wrote:
> If we change the file mtime to 1969, mksquashfs and mount,
> the atime/mtime of this file will be underflow. The reason is
> treating timestamps with the high bit set as positive
> times(before 1970), which should be set as negative times
> just like on 32 bit system. After this, the poissble range
> of timestamps will be 1901-2038(prev is 1970-2106) on 64
> bit system.
> 
> Signed-off-by: zhengbin <zhengbin13@huawei.com>
> ---
>  fs/squashfs/inode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c
> index e9793b1e49a5..03a6ef77a2d2 100644
> --- a/fs/squashfs/inode.c
> +++ b/fs/squashfs/inode.c
> @@ -72,7 +72,7 @@ static int squashfs_new_inode(struct super_block *sb, struct inode *inode,
>  	i_uid_write(inode, i_uid);
>  	i_gid_write(inode, i_gid);
>  	inode->i_ino = le32_to_cpu(sqsh_ino->inode_number);
> -	inode->i_mtime.tv_sec = le32_to_cpu(sqsh_ino->mtime);
> +	inode->i_mtime.tv_sec = (signed int)le32_to_cpu(sqsh_ino->mtime);
>  	inode->i_atime.tv_sec = inode->i_mtime.tv_sec;
>  	inode->i_ctime.tv_sec = inode->i_mtime.tv_sec;
>  	inode->i_mode = le16_to_cpu(sqsh_ino->mode);
> --
> 2.16.2.dirty
> 
> 
> .
>