[PATCH] xfs: check da node magic in _node_lookup_int

[PATCH] xfs: check da node magic in _node_lookup_int

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Before we start processing what we /think/ is a da3 node block, actually
check the magic to make sure that we're looking at a node block.  This
way we won't blow the asserts in _node_hdr_from_disk on corrupted
metadata.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_da_btree.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index 9efbd2038ffb..70e7da634f3e 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -1522,8 +1522,11 @@ xfs_da3_node_lookup_int(
 			break;
 		}
 
-		blk->magic = XFS_DA_NODE_MAGIC;
+		if (blk->magic != XFS_DA_NODE_MAGIC &&
+		    blk->magic != XFS_DA3_NODE_MAGIC)
+			return -EFSCORRUPTED;
 
+		blk->magic = XFS_DA_NODE_MAGIC;
 
 		/*
 		 * Search an intermediate node for a match.

Re: [PATCH] xfs: check da node magic in _node_lookup_int

[Dave Chinner]

On Tue, Jul 31, 2018 at 01:03:56PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Before we start processing what we /think/ is a da3 node block, actually
> check the magic to make sure that we're looking at a node block.  This
> way we won't blow the asserts in _node_hdr_from_disk on corrupted
> metadata.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_da_btree.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
> index 9efbd2038ffb..70e7da634f3e 100644
> --- a/fs/xfs/libxfs/xfs_da_btree.c
> +++ b/fs/xfs/libxfs/xfs_da_btree.c
> @@ -1522,8 +1522,11 @@ xfs_da3_node_lookup_int(
>  			break;
>  		}
>  
> -		blk->magic = XFS_DA_NODE_MAGIC;
> +		if (blk->magic != XFS_DA_NODE_MAGIC &&
> +		    blk->magic != XFS_DA3_NODE_MAGIC)
> +			return -EFSCORRUPTED;
>  
> +		blk->magic = XFS_DA_NODE_MAGIC;

Can we please use a temporary variable for the on-disk magic number
checks, then? blk->magic isn't supposed to hold the on disk format
magic number - it's just an indication of the format the current
state block points at - so using it to temporarily store the on disk
magic number for checks like this is just wrong....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: [PATCH] xfs: check da node magic in _node_lookup_int

[Darrick J. Wong]

On Wed, Aug 01, 2018 at 08:31:12AM +1000, Dave Chinner wrote:
> On Tue, Jul 31, 2018 at 01:03:56PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Before we start processing what we /think/ is a da3 node block, actually
> > check the magic to make sure that we're looking at a node block.  This
> > way we won't blow the asserts in _node_hdr_from_disk on corrupted
> > metadata.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/libxfs/xfs_da_btree.c |    5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
> > index 9efbd2038ffb..70e7da634f3e 100644
> > --- a/fs/xfs/libxfs/xfs_da_btree.c
> > +++ b/fs/xfs/libxfs/xfs_da_btree.c
> > @@ -1522,8 +1522,11 @@ xfs_da3_node_lookup_int(
> >  			break;
> >  		}
> >  
> > -		blk->magic = XFS_DA_NODE_MAGIC;
> > +		if (blk->magic != XFS_DA_NODE_MAGIC &&
> > +		    blk->magic != XFS_DA3_NODE_MAGIC)
> > +			return -EFSCORRUPTED;
> >  
> > +		blk->magic = XFS_DA_NODE_MAGIC;
> 
> Can we please use a temporary variable for the on-disk magic number
> checks, then? blk->magic isn't supposed to hold the on disk format
> magic number - it's just an indication of the format the current
> state block points at - so using it to temporarily store the on disk
> magic number for checks like this is just wrong....

Ok.

--D

> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com
> --
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