xfs: check _alloc_read_agf buffer pointer before using

commit 10479e2dea83d4c421ad05dfc55d918aa8dfc0cd upstream.

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.

Fixes-coverity-id: 1415250
Fixes-coverity-id: 1415320
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c
index e170161..d71cb63 100644 (file)
--- a/fs/xfs/libxfs/xfs_refcount.c
+++ b/fs/xfs/libxfs/xfs_refcount.c
@@ -1640,6 +1640,10 @@ 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 350fc64..0015c19 100644 (file)
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -169,6 +169,8 @@ xfs_reflink_find_shared(
        error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
        if (error)
                return error;
+       if (!agbp)
+               return -ENOMEM;
 
        cur = xfs_refcountbt_init_cursor(mp, NULL, agbp, agno, NULL);