linux-ext4 - Re: [PATCH] e2fsck: Correct ext4 dates generated by old kernels

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] [day] [month] [year] [list]

Message-ID: <1448515661.4511.2.camel@novalis.org>
Date:	Thu, 26 Nov 2015 00:27:41 -0500
From:	David Turner <novalis@...alis.org>
To:	Theodore Ts'o <tytso@....edu>
Cc:	Andreas Dilger <adilger@...ger.ca>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] e2fsck: Correct ext4 dates generated by old kernels

On Wed, 2015-11-25 at 04:46 -0500, Theodore Ts'o wrote:
> On Wed, Nov 25, 2015 at 01:01:35AM -0500, David Turner wrote:
> > On Tue, 2015-11-24 at 14:34 -0700, Andreas Dilger wrote: 
> > > +static int check_inode_extra_negative_epoch(__u32 xtime, __u32
> > > extra) {
> > > +	return (xtime & (1 << 31)) != 0 &&
> > 
> > On a re-read, I think the bitshift is technically undefined
> > behavior
> > because 1 is signed and 2**31 is not representable as a signed (32
> > -bit)
> > int. Changing it to 1U should fix it.
> 
> Instead of doing all of the bitshifts, I was thinking about doing
> something much simpler:
> 
> 	...
> 	if (inode->ctime_hi == 3 && fix_problem(....)
> 		inode->ctime_hi = 0;
> 	if (inode->mtime_hi == 3 && fix_problem(....)
> 		inode->mtime_hi = 0;
> 
> Hmm?  That should work just as well, and is easier to read and
> understand what's going on, and matches with the test we are using in
> the kernel.

I think we also need to check that the {a,c,m}time has the high bit
set.
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html