diff mbox

[3/7] xfs: filter out obviously bad btree pointers

Message ID 148582220244.12293.9617058284483534384.stgit@birch.djwong.org (mailing list archive)
State Superseded
Headers show

Commit Message

Darrick J. Wong Jan. 31, 2017, 12:23 a.m. UTC
From: Darrick J. Wong <darrick.wong@oracle.com>

Don't let anybody load an obviously bad btree pointer.  Since the values
come from disk, we must return an error, not just ASSERT.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c  |    4 +---
 fs/xfs/libxfs/xfs_btree.c |    3 ++-
 fs/xfs/libxfs/xfs_btree.h |    2 +-
 3 files changed, 4 insertions(+), 5 deletions(-)



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Comments

Eric Sandeen Jan. 31, 2017, 4:39 a.m. UTC | #1
On 1/30/17 6:23 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Don't let anybody load an obviously bad btree pointer.  Since the values
> come from disk, we must return an error, not just ASSERT.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_bmap.c  |    4 +---
>  fs/xfs/libxfs/xfs_btree.c |    3 ++-
>  fs/xfs/libxfs/xfs_btree.h |    2 +-
>  3 files changed, 4 insertions(+), 5 deletions(-)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index bfc00de..443cb10 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1291,9 +1291,7 @@ xfs_bmap_read_extents(
>  	ASSERT(level > 0);
>  	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes);
>  	bno = be64_to_cpu(*pp);
> -	ASSERT(bno != NULLFSBLOCK);
> -	ASSERT(XFS_FSB_TO_AGNO(mp, bno) < mp->m_sb.sb_agcount);
> -	ASSERT(XFS_FSB_TO_AGBNO(mp, bno) < mp->m_sb.sb_agblocks);
> +

fwiw there's an assignment of bno = NULLFSBLOCK just before here,
which is never used and overwritten in this hunk.
Could probably clean that up here too.

>  	/*
>  	 * Go down the tree until leaf level is reached, following the first
>  	 * pointer (leftmost) at each level.
> diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
> index 21e6a6a..2849d3f 100644
> --- a/fs/xfs/libxfs/xfs_btree.c
> +++ b/fs/xfs/libxfs/xfs_btree.c
> @@ -810,7 +810,8 @@ xfs_btree_read_bufl(
>  	xfs_daddr_t		d;		/* real disk block address */
>  	int			error;
>  
> -	ASSERT(fsbno != NULLFSBLOCK);
> +	if (!XFS_FSB_SANITY_CHECK(mp, fsbno))
> +		return -EFSCORRUPTED;

This does away with the NULLFSBLOCK checks though, right?

#define NULLFSBLOCK     ((xfs_fsblock_t)-1)

which is also used as an in-memory condition, so I'm not sure
it should be added to XFS_FSB_SANITY_CHECK.

IOWs some asserts about it are really code flow asserts, though
it also shouldn't be read from disk.

>  	d = XFS_FSB_TO_DADDR(mp, fsbno);
>  	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
>  				   mp->m_bsize, lock, &bp, ops);
> diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
> index b69b947..33a8f86 100644
> --- a/fs/xfs/libxfs/xfs_btree.h
> +++ b/fs/xfs/libxfs/xfs_btree.h
> @@ -456,7 +456,7 @@ static inline int xfs_btree_get_level(struct xfs_btree_block *block)
>  #define	XFS_FILBLKS_MAX(a,b)	max_t(xfs_filblks_t, (a), (b))
>  
>  #define	XFS_FSB_SANITY_CHECK(mp,fsb)	\
> -	(XFS_FSB_TO_AGNO(mp, fsb) < mp->m_sb.sb_agcount && \
> +	(fsb && XFS_FSB_TO_AGNO(mp, fsb) < mp->m_sb.sb_agcount && \
>  		XFS_FSB_TO_AGBNO(mp, fsb) < mp->m_sb.sb_agblocks)
>  
>  /*
> 
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Darrick J. Wong Jan. 31, 2017, 8:09 p.m. UTC | #2
On Mon, Jan 30, 2017 at 10:39:05PM -0600, Eric Sandeen wrote:
> On 1/30/17 6:23 PM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Don't let anybody load an obviously bad btree pointer.  Since the values
> > come from disk, we must return an error, not just ASSERT.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/libxfs/xfs_bmap.c  |    4 +---
> >  fs/xfs/libxfs/xfs_btree.c |    3 ++-
> >  fs/xfs/libxfs/xfs_btree.h |    2 +-
> >  3 files changed, 4 insertions(+), 5 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> > index bfc00de..443cb10 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.c
> > +++ b/fs/xfs/libxfs/xfs_bmap.c
> > @@ -1291,9 +1291,7 @@ xfs_bmap_read_extents(
> >  	ASSERT(level > 0);
> >  	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes);
> >  	bno = be64_to_cpu(*pp);
> > -	ASSERT(bno != NULLFSBLOCK);
> > -	ASSERT(XFS_FSB_TO_AGNO(mp, bno) < mp->m_sb.sb_agcount);
> > -	ASSERT(XFS_FSB_TO_AGBNO(mp, bno) < mp->m_sb.sb_agblocks);
> > +
> 
> fwiw there's an assignment of bno = NULLFSBLOCK just before here,
> which is never used and overwritten in this hunk.
> Could probably clean that up here too.

Yes, that could go too.

> >  	/*
> >  	 * Go down the tree until leaf level is reached, following the first
> >  	 * pointer (leftmost) at each level.
> > diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
> > index 21e6a6a..2849d3f 100644
> > --- a/fs/xfs/libxfs/xfs_btree.c
> > +++ b/fs/xfs/libxfs/xfs_btree.c
> > @@ -810,7 +810,8 @@ xfs_btree_read_bufl(
> >  	xfs_daddr_t		d;		/* real disk block address */
> >  	int			error;
> >  
> > -	ASSERT(fsbno != NULLFSBLOCK);
> > +	if (!XFS_FSB_SANITY_CHECK(mp, fsbno))
> > +		return -EFSCORRUPTED;
> 
> This does away with the NULLFSBLOCK checks though, right?
> 
> #define NULLFSBLOCK     ((xfs_fsblock_t)-1)
> 
> which is also used as an in-memory condition, so I'm not sure
> it should be added to XFS_FSB_SANITY_CHECK.

[reiterating our irc conversation]

It shouldn't, since XFS_FSB_TO_AGNO(mp, NULLFSBLOCK) ought to produce
NULLAGNUMBER, which will still fail the check.

> IOWs some asserts about it are really code flow asserts, though
> it also shouldn't be read from disk.

xfs_btree_read_bufl is called by xfs_bmap_check_leaf_extents, which is
the verifier of the on-disk data.

--D

> >  	d = XFS_FSB_TO_DADDR(mp, fsbno);
> >  	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
> >  				   mp->m_bsize, lock, &bp, ops);
> > diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
> > index b69b947..33a8f86 100644
> > --- a/fs/xfs/libxfs/xfs_btree.h
> > +++ b/fs/xfs/libxfs/xfs_btree.h
> > @@ -456,7 +456,7 @@ static inline int xfs_btree_get_level(struct xfs_btree_block *block)
> >  #define	XFS_FILBLKS_MAX(a,b)	max_t(xfs_filblks_t, (a), (b))
> >  
> >  #define	XFS_FSB_SANITY_CHECK(mp,fsb)	\
> > -	(XFS_FSB_TO_AGNO(mp, fsb) < mp->m_sb.sb_agcount && \
> > +	(fsb && XFS_FSB_TO_AGNO(mp, fsb) < mp->m_sb.sb_agcount && \
> >  		XFS_FSB_TO_AGBNO(mp, fsb) < mp->m_sb.sb_agblocks)
> >  
> >  /*
> > 
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Eric Sandeen Jan. 31, 2017, 8:37 p.m. UTC | #3
On 1/31/17 2:09 PM, Darrick J. Wong wrote:
>>> diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
>>> index 21e6a6a..2849d3f 100644
>>> --- a/fs/xfs/libxfs/xfs_btree.c
>>> +++ b/fs/xfs/libxfs/xfs_btree.c
>>> @@ -810,7 +810,8 @@ xfs_btree_read_bufl(
>>>  	xfs_daddr_t		d;		/* real disk block address */
>>>  	int			error;
>>>  
>>> -	ASSERT(fsbno != NULLFSBLOCK);
>>> +	if (!XFS_FSB_SANITY_CHECK(mp, fsbno))
>>> +		return -EFSCORRUPTED;
>> This does away with the NULLFSBLOCK checks though, right?
>>
>> #define NULLFSBLOCK     ((xfs_fsblock_t)-1)
>>
>> which is also used as an in-memory condition, so I'm not sure
>> it should be added to XFS_FSB_SANITY_CHECK.
> [reiterating our irc conversation]
> 
> It shouldn't, since XFS_FSB_TO_AGNO(mp, NULLFSBLOCK) ought to produce
> NULLAGNUMBER, which will still fail the check.

Oh, sure.  sorry for missing that.

Looks ok after all.  :)

Reviewed-by: Eric Sandeen <sandeen@redhat.com>

>> IOWs some asserts about it are really code flow asserts, though
>> it also shouldn't be read from disk.
> xfs_btree_read_bufl is called by xfs_bmap_check_leaf_extents, which is
> the verifier of the on-disk data.
> 
> --D
> 
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diff mbox

Patch

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index bfc00de..443cb10 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1291,9 +1291,7 @@  xfs_bmap_read_extents(
 	ASSERT(level > 0);
 	pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes);
 	bno = be64_to_cpu(*pp);
-	ASSERT(bno != NULLFSBLOCK);
-	ASSERT(XFS_FSB_TO_AGNO(mp, bno) < mp->m_sb.sb_agcount);
-	ASSERT(XFS_FSB_TO_AGBNO(mp, bno) < mp->m_sb.sb_agblocks);
+
 	/*
 	 * Go down the tree until leaf level is reached, following the first
 	 * pointer (leftmost) at each level.
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 21e6a6a..2849d3f 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -810,7 +810,8 @@  xfs_btree_read_bufl(
 	xfs_daddr_t		d;		/* real disk block address */
 	int			error;
 
-	ASSERT(fsbno != NULLFSBLOCK);
+	if (!XFS_FSB_SANITY_CHECK(mp, fsbno))
+		return -EFSCORRUPTED;
 	d = XFS_FSB_TO_DADDR(mp, fsbno);
 	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
 				   mp->m_bsize, lock, &bp, ops);
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index b69b947..33a8f86 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -456,7 +456,7 @@  static inline int xfs_btree_get_level(struct xfs_btree_block *block)
 #define	XFS_FILBLKS_MAX(a,b)	max_t(xfs_filblks_t, (a), (b))
 
 #define	XFS_FSB_SANITY_CHECK(mp,fsb)	\
-	(XFS_FSB_TO_AGNO(mp, fsb) < mp->m_sb.sb_agcount && \
+	(fsb && XFS_FSB_TO_AGNO(mp, fsb) < mp->m_sb.sb_agcount && \
 		XFS_FSB_TO_AGBNO(mp, fsb) < mp->m_sb.sb_agblocks)
 
 /*