[stable][PATCH < 2.6.19] Fix data corruption with dm-crypt over RAID5

[stable][PATCH < 2.6.19] Fix data corruption with dm-crypt over RAID5

[Christophe Saout]

Fix corruption issue with dm-crypt on top of software raid5. Cancelled
readahead bio's that report no error, just have BIO_UPTODATE cleared
were reported as successful reads to the higher layers (and leaving
random content in the buffer cache). Already fixed in 2.6.19.

Signed-off-by: Christophe Saout <christophe@saout.de>


--- linux-2.6.18.orig/drivers/md/dm-crypt.c	2006-09-20 05:42:06.000000000 +0200
+++ linux-2.6.18/drivers/md/dm-crypt.c	2006-12-02 03:03:36.000000000 +0100
@@ -717,13 +717,15 @@
 	if (bio->bi_size)
 		return 1;
 
+	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
+		error = -EIO;
+                        
 	bio_put(bio);
 
 	/*
 	 * successful reads are decrypted by the worker thread
 	 */
-	if ((bio_data_dir(bio) == READ)
-	    && bio_flagged(bio, BIO_UPTODATE)) {
+	if (bio_data_dir(io->bio) == READ && !error) {
 		kcryptd_queue_io(io);
 		return 0;
 	}

Re: [stable][PATCH < 2.6.19] Fix data corruption with dm-crypt over RAID5

[Chris Wright]

[Note: please Cc: stable@kernel.org on -stable patches]

* Christophe Saout (christophe@saout.de) wrote:
> Fix corruption issue with dm-crypt on top of software raid5. Cancelled
> readahead bio's that report no error, just have BIO_UPTODATE cleared
> were reported as successful reads to the higher layers (and leaving
> random content in the buffer cache). Already fixed in 2.6.19.

I take it this is fixed a different way in 2.6.19?  Mind clarifying the
difference?

> Signed-off-by: Christophe Saout <christophe@saout.de>
> 
> 
> --- linux-2.6.18.orig/drivers/md/dm-crypt.c	2006-09-20 05:42:06.000000000 +0200
> +++ linux-2.6.18/drivers/md/dm-crypt.c	2006-12-02 03:03:36.000000000 +0100
> @@ -717,13 +717,15 @@
>  	if (bio->bi_size)
>  		return 1;
>  
> +	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
> +		error = -EIO;
> +                        

Minor nit:  introduces trailing whitespaces, cleaned it up locally.

thanks,
-chris
--

This is a note to let you know that we have just queued up the patch titled

    Subject: dm crypt: Fix data corruption with dm-crypt over RAID5

to the 2.6.18-stable tree.  Its filename is

    dm-crypt-fix-data-corruption-with-dm-crypt-over-raid5.patch

A git repo of this tree can be found at 
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary


>From linux-kernel-owner+chrisw=40sous-sol.org-S1162719AbWLBC2Z@vger.kernel.org  Fri Dec  1 18:36:19 2006
Date: 	Sat, 02 Dec 2006 03:27:56 +0100
From: Christophe Saout <christophe@saout.de>
To: linux-kernel@vger.kernel.org
Cc: dm-crypt@saout.de, Andrey <dm-crypt-revealed-address@lelik.org>, Andrew Morton <akpm@osdl.org>, agk@redhat.com, Neil Brown <neilb@suse.de>, Jens Axboe <jens.axboe@oracle.com>, Chris Wright <chrisw@sous-sol.org>
Subject: dm crypt: Fix data corruption with dm-crypt over RAID5

Fix corruption issue with dm-crypt on top of software raid5. Cancelled
readahead bio's that report no error, just have BIO_UPTODATE cleared
were reported as successful reads to the higher layers (and leaving
random content in the buffer cache). Already fixed in 2.6.19.

Signed-off-by: Christophe Saout <christophe@saout.de>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
 drivers/md/dm-crypt.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- linux-2.6.18.5.orig/drivers/md/dm-crypt.c
+++ linux-2.6.18.5/drivers/md/dm-crypt.c
@@ -717,13 +717,15 @@ static int crypt_endio(struct bio *bio, 
 	if (bio->bi_size)
 		return 1;
 
+	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
+		error = -EIO;
+
 	bio_put(bio);
 
 	/*
 	 * successful reads are decrypted by the worker thread
 	 */
-	if ((bio_data_dir(bio) == READ)
-	    && bio_flagged(bio, BIO_UPTODATE)) {
+	if (bio_data_dir(io->bio) == READ && !error) {
 		kcryptd_queue_io(io);
 		return 0;
 	}

Re: [stable][PATCH < 2.6.19] Fix data corruption with dm-crypt over RAID5

[Christophe Saout]

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Am Freitag, den 01.12.2006, 19:49 -0800 schrieb Chris Wright:

> * Christophe Saout (christophe@saout.de) wrote:
> > Fix corruption issue with dm-crypt on top of software raid5. Cancelled
> > readahead bio's that report no error, just have BIO_UPTODATE cleared
> > were reported as successful reads to the higher layers (and leaving
> > random content in the buffer cache). Already fixed in 2.6.19.
> 
> I take it this is fixed a different way in 2.6.19?  Mind clarifying the
> difference?

It's more or less fixed the same way in 2.6.19. The function was
reordered by Milan Broz to accommodate the changed write path (commit
8b004457168995f2ae2a35327f885183a9e74141):

> [PATCH] dm crypt: restructure for workqueue change
>
> Restructure part of the dm-crypt code in preparation for workqueue
> changes.
>
> Use 'base_bio' or 'clone' variable names consistently throughout.  No
> functional changes are included in this patch.

"No functional changes" actually included the correct fix, accidental or
not.

> Minor nit:  introduces trailing whitespaces, cleaned it up locally.

Ouch, sorry.


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Re: [dm-devel] [stable][PATCH < 2.6.19] Fix data corruption with dm-crypt over RAID5

[Piet Delaney]

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On Sat, 2006-12-02 at 03:27 +0100, Christophe Saout wrote:

Hi Christophe:

I'm wondering about trying out your patch with dm-crypt on 2.6.12. 
The code in drivers/md/dm-crypt.c`crypt_endio() appears to be the same.

Is there a reason that this isn't necessary or would be a bad idea.
Looks like the existing code isn't checking the BIO_UPTODATE flag
before doing the bio_put(). Looks the the second part of not calling
kcryptd_queue_io() and forwarding the processing to the cryptd is
effectively the same. The 1st change will set error if BIO_UPTODATE
isn't set and that will cause the 2nd change to skip calling 
kcryptd_queue_io().

I'm not sure about the change in the arg to bio_data_dir() 
changing from bio to io->bio. Perhaps they are equivalent;
care to comment on that.

Unless I hear otherwise I'll try it out Tomorrow.

-piet

> Fix corruption issue with dm-crypt on top of software raid5. Cancelled
> readahead bio's that report no error, just have BIO_UPTODATE cleared
> were reported as successful reads to the higher layers (and leaving
> random content in the buffer cache). Already fixed in 2.6.19.
> 
> Signed-off-by: Christophe Saout <christophe@saout.de>
> 
> 
> --- linux-2.6.18.orig/drivers/md/dm-crypt.c	2006-09-20 05:42:06.000000000 +0200
> +++ linux-2.6.18/drivers/md/dm-crypt.c	2006-12-02 03:03:36.000000000 +0100
> @@ -717,13 +717,15 @@
>  	if (bio->bi_size)
>  		return 1;
>  
> +	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
> +		error = -EIO;
> +                        
>  	bio_put(bio);
>  
>  	/*
>  	 * successful reads are decrypted by the worker thread
>  	 */
> -	if ((bio_data_dir(bio) == READ)
> -	    && bio_flagged(bio, BIO_UPTODATE)) {
> +	if (bio_data_dir(io->bio) == READ && !error) {
>  		kcryptd_queue_io(io);
>  		return 0;
>  	}
> 
> 
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
-- 
Piet Delaney                                    Phone: (408) 200-5256
Blue Lane Technologies                          Fax:   (408) 200-5299
10450 Bubb Rd.
Cupertino, Ca. 95014                            Email: piet@bluelane.com

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Re: [stable][PATCH < 2.6.19] Fix data corruption with dm-crypt over RAID5

[Piet Delaney]

Christophe Saout wrote:

> Fix corruption issue with dm-crypt on top of software raid5. Cancelled
> readahead bio's that report no error, just have BIO_UPTODATE cleared
> were reported as successful reads to the higher layers (and leaving
> random content in the buffer cache). Already fixed in 2.6.19.
> 
> Signed-off-by: Christophe Saout <christophe@saout.de>
> 
> 
> --- linux-2.6.18.orig/drivers/md/dm-crypt.c   2006-09-20 05:42:06.000000000
> +0200
> +++ linux-2.6.18/drivers/md/dm-crypt.c        2006-12-02 03:03:36.000000000 +0100
> @@ -717,13 +717,15 @@
>  if (bio->bi_size)
>  return 1;
>  
> +     if (!bio_flagged(bio, BIO_UPTODATE) && !error)
> +             error = -EIO;
> +
>  bio_put(bio);
>  
>  /*
>  * successful reads are decrypted by the worker thread
>  */
> -     if ((bio_data_dir(bio) == READ)
> -         && bio_flagged(bio, BIO_UPTODATE)) {
> +     if (bio_data_dir(io->bio) == READ && !error) {
>  kcryptd_queue_io(io);

Why doesn't kcryptd_queue_io() check the return value from queue_work()?


    476 static void kcryptd_queue_io(struct crypt_io *io)
    477 {
    478         INIT_WORK(&io->work, kcryptd_do_work, io);
    479         queue_work(_kcryptd_workqueue, &io->work);
    480 }

-piet

>  return 0;
>  }