• Darrick J. Wong's avatar
    xfs: don't crash on unexpected holes in dir/attr btrees · cd87d867
    Darrick J. Wong authored
    In quite a few places we call xfs_da_read_buf with a mappedbno that we
    don't control, then assume that the function passes back either an error
    code or a buffer pointer.  Unfortunately, if mappedbno == -2 and bno
    maps to a hole, we get a return code of zero and a NULL buffer, which
    means that we crash if we actually try to use that buffer pointer.  This
    happens immediately when we set the buffer type for transaction context.
    
    Therefore, check that we have no error code and a non-NULL bp before
    trying to use bp.  This patch is a follow-up to an incomplete fix in
    96a3aefb ("xfs: don't crash if reading a directory results in an
    unexpected hole").
    Signed-off-by: 's avatarDarrick J. Wong <darrick.wong@oracle.com>
    cd87d867