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    Subject[PATCH 5.5 188/257] XArray: Fix xas_pause for large multi-index entries
    Date
    From: Matthew Wilcox (Oracle) <willy@infradead.org>

    commit c36d451ad386b34f452fc3c8621ff14b9eaa31a6 upstream.

    Inspired by the recent Coverity report, I looked for other places where
    the offset wasn't being converted to an unsigned long before being
    shifted, and I found one in xas_pause() when the entry being paused is
    of order >32.

    Fixes: b803b42823d0 ("xarray: Add XArray iterators")
    Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
    Cc: stable@vger.kernel.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    lib/test_xarray.c | 37 +++++++++++++++++++++++++++++++++++++
    lib/xarray.c | 2 +-
    2 files changed, 38 insertions(+), 1 deletion(-)

    --- a/lib/test_xarray.c
    +++ b/lib/test_xarray.c
    @@ -1156,6 +1156,42 @@ static noinline void check_find_entry(st
    XA_BUG_ON(xa, !xa_empty(xa));
    }

    +static noinline void check_pause(struct xarray *xa)
    +{
    + XA_STATE(xas, xa, 0);
    + void *entry;
    + unsigned int order;
    + unsigned long index = 1;
    + unsigned int count = 0;
    +
    + for (order = 0; order < order_limit; order++) {
    + XA_BUG_ON(xa, xa_store_order(xa, index, order,
    + xa_mk_index(index), GFP_KERNEL));
    + index += 1UL << order;
    + }
    +
    + rcu_read_lock();
    + xas_for_each(&xas, entry, ULONG_MAX) {
    + XA_BUG_ON(xa, entry != xa_mk_index(1UL << count));
    + count++;
    + }
    + rcu_read_unlock();
    + XA_BUG_ON(xa, count != order_limit);
    +
    + count = 0;
    + xas_set(&xas, 0);
    + rcu_read_lock();
    + xas_for_each(&xas, entry, ULONG_MAX) {
    + XA_BUG_ON(xa, entry != xa_mk_index(1UL << count));
    + count++;
    + xas_pause(&xas);
    + }
    + rcu_read_unlock();
    + XA_BUG_ON(xa, count != order_limit);
    +
    + xa_destroy(xa);
    +}
    +
    static noinline void check_move_tiny(struct xarray *xa)
    {
    XA_STATE(xas, xa, 0);
    @@ -1664,6 +1700,7 @@ static int xarray_checks(void)
    check_xa_alloc();
    check_find(&array);
    check_find_entry(&array);
    + check_pause(&array);
    check_account(&array);
    check_destroy(&array);
    check_move(&array);
    --- a/lib/xarray.c
    +++ b/lib/xarray.c
    @@ -970,7 +970,7 @@ void xas_pause(struct xa_state *xas)

    xas->xa_node = XAS_RESTART;
    if (node) {
    - unsigned int offset = xas->xa_offset;
    + unsigned long offset = xas->xa_offset;
    while (++offset < XA_CHUNK_SIZE) {
    if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
    break;

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