Date:	Wed, 21 Jan 2009 23:50:02 -0600
From:	Felix Blyakher <felixb@....com>
To:	Dave Chinner <david@...morbit.com>
Cc:	Nick Piggin <nickpiggin@...oo.com.au>,
	Eric Sesterhenn <snakebyte@....de>,
	linux-kernel@...r.kernel.org, xfs@....sgi.com,
	Pavel Machek <pavel@...e.cz>, npiggin@...oo.com.au,
	Chris Mason <chris.mason@...cle.com>
Subject: Re: [PATCH] Re: Corrupted XFS log replay oops.


On Jan 21, 2009, at 10:37 PM, Dave Chinner wrote:

> On Wed, Jan 21, 2009 at 03:03:06PM +1100, Nick Piggin wrote:
>> On Wednesday 21 January 2009 14:57:03 Dave Chinner wrote:
>>>> [  235.250167] ------------[ cut here ]------------
>>>> [  235.250354] kernel BUG at mm/vmalloc.c:164!
>>>> [  235.250478] invalid opcode: 0000 [#1] PREEMPT DEBUG_PAGEALLOC
>>>> [  235.250869] last sysfs file: /sys/block/ram9/range
>>>> [  235.250998] Modules linked in:
> ......
>>>> [  235.251037] Call Trace:
>>>> [  235.251037]  [<c01414cf>] ? trace_hardirqs_on+0xb/0xd
>>>> [  235.251037]  [<c018367c>] ? vm_map_ram+0x36e/0x38a
>>>> [  235.251037]  [<c03b2e1e>] ? _xfs_buf_map_pages+0x42/0x6d
>>>> [  235.251037]  [<c03b3773>] ? xfs_buf_get_noaddr+0xbc/0x11f
>>>> [  235.251037]  [<c03a2406>] ? xlog_get_bp+0x5a/0x5d
>>>> [  235.251037]  [<c03a28fa>] ? xlog_find_verify_log_record 
>>>> +0x26/0x208
>>>> [  235.251037]  [<c03a3521>] ? xlog_find_zeroed+0x1d6/0x214
>>>> [  235.251037]  [<c03a3584>] ? xlog_find_head+0x25/0x358
>>>
>>> .....
>>>
>>> Ok, that's crashing in the new vmap code. It might take a couple
>>> of days before I get a chance to look at this, but I've cc'd Nick  
>>> Piggin
>>> in case he has a chance to look at it before that. It's probably
>>> an XFS bug, anyway.
>>
>> Hmm, it is crashing in BUG_ON(addr >= end); where this could happen
>> if XFS asks to map a really huge (or -ve) number of pages and wraps
>> the range, or if vmap subsystem returns an address right near the
>> end of the address range and addr+size wraps (which would be a bug
>> in vmap of course, but I think maybe less likely).
>
> It's a zero length range, not a negative value. A debug XFS would
> have assert failed on it, but it was completely unchecked on
> production builds. The following patch checks the length of blocks
> to build/read/write for being valid. Instead of an oops, we get:
>
> [ 1572.665001] XFS mounting filesystem loop0
> [ 1572.666942] XFS: Invalid block length (0x0) given for buffer
> [ 1572.667141] XFS: Log inconsistent (didn't find previous header)
> [ 1572.667141] XFS: empty log check failed
> [ 1572.667141] XFS: log mount/recovery failed: error 5
> [ 1572.671487] XFS: log mount failed
>
> Cheers,
>
> Dave.
> -- 
> Dave Chinner
> david@...morbit.com
>
> [XFS] Check buffer lengths in log recovery
>
> Before trying to obtain, read or write a buffer,
> check that the buffer length is actually valid. If
> it is not valid, then something read in the recovery
> process has been corrupted and we should abort
> recovery.
>
> Reported-by: Eric Sesterhenn <snakebyte@....de>

Reviewed-by: Felix Blyakher <felixb@....com>

> ---
>  fs/xfs/xfs_log_recover.c |   31 +++++++++++++++++++++++++------
>  1 files changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index 35cca98..b1047de 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -70,16 +70,21 @@ STATIC void	xlog_recover_check_summary(xlog_t *);
>  xfs_buf_t *
>  xlog_get_bp(
>  	xlog_t		*log,
> -	int		num_bblks)
> +	int		nbblks)
>  {
> -	ASSERT(num_bblks > 0);
> +	if (nbblks <= 0 || nbblks > log->l_logBBsize) {
> +		xlog_warn("XFS: Invalid block length (0x%x) given for buffer",  
> nbblks);
> +		XFS_ERROR_REPORT("xlog_get_bp(1)",
> +				 XFS_ERRLEVEL_HIGH, log->l_mp);
> +		return NULL;
> +	}
>
>  	if (log->l_sectbb_log) {
> -		if (num_bblks > 1)
> -			num_bblks += XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
> -		num_bblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, num_bblks);
> +		if (nbblks > 1)
> +			nbblks += XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
> +		nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
>  	}
> -	return xfs_buf_get_noaddr(BBTOB(num_bblks), log->l_mp- 
> >m_logdev_targp);
> +	return xfs_buf_get_noaddr(BBTOB(nbblks), log->l_mp->m_logdev_targp);
>  }
>
>  void
> @@ -102,6 +107,13 @@ xlog_bread(
>  {
>  	int		error;
>
> +	if (nbblks <= 0 || nbblks > log->l_logBBsize) {
> +		xlog_warn("XFS: Invalid block length (0x%x) given for buffer",  
> nbblks);
> +		XFS_ERROR_REPORT("xlog_bread(1)",
> +				 XFS_ERRLEVEL_HIGH, log->l_mp);
> +		return EFSCORRUPTED;
> +	}
> +
>  	if (log->l_sectbb_log) {
>  		blk_no = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, blk_no);
>  		nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
> @@ -139,6 +151,13 @@ xlog_bwrite(
>  {
>  	int		error;
>
> +	if (nbblks <= 0 || nbblks > log->l_logBBsize) {
> +		xlog_warn("XFS: Invalid block length (0x%x) given for buffer",  
> nbblks);
> +		XFS_ERROR_REPORT("xlog_bwrite(1)",
> +				 XFS_ERRLEVEL_HIGH, log->l_mp);
> +		return EFSCORRUPTED;
> +	}
> +
>  	if (log->l_sectbb_log) {
>  		blk_no = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, blk_no);
>  		nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
>
> _______________________________________________
> xfs mailing list
> xfs@....sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

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