[PATCH] xfs: fix missing error check in xfs_rtfree_range

[PATCH] xfs: fix missing error check in xfs_rtfree_range

[Dave Chinner]

When xfs_rtfind_forw() returns an error, the block is returned
uninitialised.  xfs_rtfree_range() is not checking the error return,
so could be using an uninitialised block number for modifying bitmap
summary info.

The problem was found by gcc when compiling the *userspace* libxfs
code - it is an copy of the kernel code with the exact same bug.
gcc gives an uninitialised variable warning on the userspace code
but not on the kernel code. You gotta love the consistency (Mmmm,
slightly chewy today!).

Signed-off-by: Dave Chinner <david@fromorbit.com>
---
 fs/xfs/xfs_rtalloc.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 9e15a11..6be05f7 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1517,6 +1517,8 @@ xfs_rtfree_range(
 	 */
 	error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
 		&postblock);
+	if (error)
+		return error;
 	/*
 	 * If there are blocks not being freed at the front of the
 	 * old extent, add summary data for them to be allocated.
-- 
1.6.5

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RE: [PATCH] xfs: fix missing error check in xfs_rtfree_range

[Alex Elder]

Dave Chinner wrote:
> When xfs_rtfind_forw() returns an error, the block is returned
> uninitialised.  xfs_rtfree_range() is not checking the error return,
> so could be using an uninitialised block number for modifying bitmap
> summary info.
> 
> The problem was found by gcc when compiling the *userspace* libxfs
> code - it is an copy of the kernel code with the exact same bug.
> gcc gives an uninitialised variable warning on the userspace code
> but not on the kernel code. You gotta love the consistency (Mmmm,
> slightly chewy today!).

Looks good.  I'll send this for 2.6.33-rc4.

> Signed-off-by: Dave Chinner <david@fromorbit.com>

Reviewed-by: Alex Elder <aelder@sgi.com>


>  fs/xfs/xfs_rtalloc.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
> index 9e15a11..6be05f7 100644
> --- a/fs/xfs/xfs_rtalloc.c
> +++ b/fs/xfs/xfs_rtalloc.c
> @@ -1517,6 +1517,8 @@ xfs_rtfree_range(
>  	 */
>  	error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
>  		&postblock);
> +	if (error)
> +		return error;
>  	/*
>  	 * If there are blocks not being freed at the front of the
>  	 * old extent, add summary data for them to be allocated.

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