linux-kernel - Re: [PATCH] Update atime from future.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20121204194106.GA2200@lenny.home.zabbo.net>
Date:	Tue, 4 Dec 2012 11:41:06 -0800
From:	Zach Brown <zab@...bo.net>
To:	yangsheng <sickamd@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	adilger@...ger.ca
Subject: Re: [PATCH] Update atime from future.

On Tue, Dec 04, 2012 at 01:56:39AM +0800, yangsheng wrote:
> Relatime should update the inode atime if it is more than a day in the
> future.  The original problem seen was a tarball that had a bad atime,
> but could also happen if someone fat-fingers a "touch".  The future
> atime will never be fixed.  Before the relatime patch, the future atime
> would be updated back to the current time on the next access.

I guess.

>  	/*
> +	 * Is the previous atime value in future? If yes,
> +	 * update atime:
> +	 */
> +	if ((long)(now.tv_sec - inode->i_atime.tv_sec) < -RELATIME_MARGIN)
> +		return 1;

But this is confusing to read.  "If atime is less than a negative day in
the past.. wait, what?"

It seems like we should combine the two RELATIME_MARGIN tests.

	/*
	 * Update atime if it's older than a day or more than a day
	 * in the future, which we assume is corrupt.
	 */
	if (abs(inode->i_atime.tv_sec - now.tv_sec)) >= RELATIME_MARGIN)
		return 1;

(I don't know if you'd still need the (long) cast in there, given the
type tests in abs()).

- z
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/