[Bug 23732] New: ext4 timestamp range contains 68-year gaps

[Bug 23732] New: ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

           Summary: ext4 timestamp range contains 68-year gaps
           Product: File System
           Version: 2.5
    Kernel Version: 2.6.35
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: ext4
        AssignedTo: fs_ext4@kernel-bugs.osdl.org
        ReportedBy: mh8928@yahoo.com
        Regression: No


When 256-byte inodes are used, ext4 attempts to extend the tv_sec
portion of file timestamps from 32 to 34 bits on 64-bit systems,
presumably to defer the Y2038 problem.  However the code to do
this still fails in 2038.  Nevertheless, some timestamps beyond
the year 2038 work correctly.

Using 2.6.35/x86_64 on ext4 with 256-byte inodes:

markh@zacc:~$ touch -d 2038-01-31 /test/2038
markh@zacc:~$ touch -d 2106-02-22 /test/2106
markh@zacc:~$ ls -l /test/2038 /test/2106
-rw-r--r-- 1 markh markh 0 2038-01-31 00:00 /test/2038
-rw-r--r-- 1 markh markh 0 2106-02-22 00:00 /test/2106
markh@zacc:~$ sudo umount /test
markh@zacc:~$ sudo mount /dev/sda2 /test
markh@zacc:~$ ls -l /test/2038 /test/2106
-rw-r--r-- 1 markh markh 0 1901-12-25 17:31 /test/2038
-rw-r--r-- 1 markh markh 0 2106-02-22 00:00 /test/2106
markh@zacc:~$ 

The problem is in fs/ext4/ext.h.  The macros EXT4_INODE_GET_XTIME
and EXT4_EINODE_GET_XTIME sign-extend the low 32 bits of tv_sec,
and then ext4_decode_extra_time uses "|=" to tack on the 2
additional bits.  However if bit 31 is 1, bits 32..63 will always
be 1 due to the sign extension regardless of the 2 extra bits:

static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra)
{
       if (sizeof(time->tv_sec) > 4)
           time->tv_sec |= (__u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK)
                   << 32;
       time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >>
EXT4_EPOCH_BITS;
}

...

#define EXT4_INODE_GET_XTIME(xtime, inode, raw_inode)                   \
do {                                           \
    (inode)->xtime.tv_sec = (signed)le32_to_cpu((raw_inode)->xtime);       \
    if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra))     \
        ext4_decode_extra_time(&(inode)->xtime,                   \
                       raw_inode->xtime ## _extra);           \
} while (0)


It is not clear what time range was intended to be handled,
but the range should be continuous.  Preferably it would be the
range -0x80000000 (1901-12-13) to 0x37fffffff (2446-05-10),
in order to handle all legacy 32-bit timestamps and as many
consecutive future dates as possible.

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |alan@lxorguk.ukuu.org.uk
     Kernel Version|2.6.35                      |3.6-rc1




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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

Conrad Meyer <cse.cem@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |cse.cem@gmail.com

--- Comment #1 from Conrad Meyer <cse.cem@gmail.com> ---
Impressively, this bug is still present in v3.14-rc8.

$ touch -d 2038-01-31 test-123
$ sudo sh -c "echo 3 > /proc/sys/vm/drop_caches"
$ ls -ld test-123
drwxrwxr-x 2 cmeyer cmeyer 4096 Dec 25  1901 test-123

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

--- Comment #2 from Conrad Meyer <cse.cem@gmail.com> ---
Patch submitted, seems to fix the issue on my system.

https://lkml.org/lkml/2014/3/30/40

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

--- Comment #3 from Conrad Meyer <cse.cem@gmail.com> ---
34 (signed) bits of seconds gets us to Y2242:

$ touch -d 2242-01-01 test-123
$ sync ;sudo sh -c "echo 3 > /proc/sys/vm/drop_caches"; sleep 1; sudo sh -c
"echo 3 > /proc/sys/vm/drop_caches"; sleep 1; ls -ld test-123
drwxrwxr-x 2 cmeyer cmeyer 4096 Jan  1  2242 test-123
$ touch -d 2243-01-01 test-123
$ sync ;sudo sh -c "echo 3 > /proc/sys/vm/drop_caches"; sleep 1; sudo sh -c
"echo 3 > /proc/sys/vm/drop_caches"; sleep 1; ls -ld test-123
drwxrwxr-x 2 cmeyer cmeyer 4096 Aug  3  1698 test-123

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

--- Comment #4 from Conrad Meyer <cse.cem@gmail.com> ---
(Which we expect, given:)

$ echo $((1970+(2038-1970)*4))
2242

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

--- Comment #5 from Conrad Meyer <cse.cem@gmail.com> ---
Hm, ignore my patch I guess. Some historical context:

http://thread.gmane.org/gmane.comp.file-systems.ext4/40978

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |CODE_FIX

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[Bug 23732] ext4 timestamp range contains 68-year gaps

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https://bugzilla.kernel.org/show_bug.cgi?id=23732

--- Comment #6 from Conrad Meyer <cse.cem@gmail.com> ---
> RESOLVED CODE_FIX

Alan, what patch fixed it (sha1)? Thanks!

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

--- Comment #7 from Alan <alan@lxorguk.ukuu.org.uk> ---
I don't have the number. I re-ran your test case

[root@localhost next]# touch -d 2038-01-31 test-123
[root@localhost next]# ls -l test-123
-rw-r--r--. 1 root root 0 Jan 31  2038 test-123
[root@localhost next]# echo 3 >/proc/sys/vm/drop_caches 
[root@localhost next]# ls -l test-123
-rw-r--r--. 1 root root 0 Jan 31  2038 test-123

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

--- Comment #8 from Conrad Meyer <cse.cem@gmail.com> ---
The test case is 'touch -d 2243-01-01 test-123'... 2038 works fine.

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[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

--- Comment #9 from Conrad Meyer <cse.cem@gmail.com> ---
Hm, 2243 appears to work now too. *Shrug*.

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Re: [Bug 23732] ext4 timestamp range contains 68-year gaps

[Andreas Dilger]

On Feb 19, 2015, at 9:01 AM, bugzilla-daemon@bugzilla.kernel.org wrote:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=23732
> 
> Alan <alan@lxorguk.ukuu.org.uk> changed:
> 
>           What    |Removed                     |Added
> --------------------------------------------------------------------
>             Status|NEW                         |RESOLVED
>         Resolution|---                         |CODE_FIX

I see Alan closed this bug, but I don't see what was done to actually
fix it?  The patches from last year about this time didn't land AFAICS:

  [PATCH v8 1/2] ext4: Fix handling of extended tv_sec (bug 23732)
  [PATCH v8 2/2] e2fsck: Correct ext4 dates generated by old kernels

or did this get fixed in some other way?

Cheers, Andreas

[Bug 23732] ext4 timestamp range contains 68-year gaps

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=23732

Theodore Tso <tytso@mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |tytso@mit.edu
         Resolution|CODE_FIX                    |---

--- Comment #10 from Theodore Tso <tytso@mit.edu> ---
I'm not sure why the test cases have been passing but the true fix hasn't been
applied yet.  This is due to my not having time and the need for us to have
better test cases in e2fsprogs (for both the old and new encodings, etc.)   As
usual, the highly urgent problems with short-term deadlines tend to get higher
priority from the important long-term items.

Specifically, I want to be able to convert time strings to integers using both
the old the new encodings, and then have test cases to make sure that e2fsck
and the kernel are doing the right thing and coverting as necessary as we had
determined in the migration plan for this bug.

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[Bug 23732] ext4 timestamp range contains 68-year gaps

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https://bugzilla.kernel.org/show_bug.cgi?id=23732

Theodore Tso <tytso@mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|---                         |CODE_FIX

--- Comment #11 from Theodore Tso <tytso@mit.edu> ---
This has been fixed in the latest kernel and e2fsprogs

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