XArray: Fix xas_pause for large multi-index entries

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

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 8c7d7a8..d4f9792 100644 (file)
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -1156,6 +1156,42 @@ static noinline void check_find_entry(struct xarray *xa)
        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);

diff --git a/lib/xarray.c b/lib/xarray.c
index acd1fad..05324cf 100644 (file)
--- 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;