On Tue, Jul 18, 2017 at 11:24:28AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> In some circumstances, _alloc_read_agf can return an error code of zero
> but also a null AGF buffer pointer. Check for this and jump out.
>
It looks like this is only possible in trylock cases. Otherwise (and
unless I'm missing something), it should always return a buffer or
error.
This is circuitous regardless and so seems fine if it shuts up a
coverity warning:
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> Fixes-coverity-id: 1415250
> Fixes-coverity-id: 1415320
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_refcount.c | 4 ++++
> fs/xfs/xfs_reflink.c | 2 ++
> 2 files changed, 6 insertions(+)
>
>
> diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c
> index 900ea23..45b1c3b 100644
> --- a/fs/xfs/libxfs/xfs_refcount.c
> +++ b/fs/xfs/libxfs/xfs_refcount.c
> @@ -1638,6 +1638,10 @@ xfs_refcount_recover_cow_leftovers(
> error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
> if (error)
> goto out_trans;
> + if (!agbp) {
> + error = -ENOMEM;
> + goto out_trans;
> + }
> cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL);
>
> /* Find all the leftover CoW staging extents. */
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index d9b3d57..f45fbf0 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -170,6 +170,8 @@ xfs_reflink_find_shared(
> error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
> if (error)
> return error;
> + if (!agbp)
> + return -ENOMEM;
>
> cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL);
>
>
> --
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