[PATCH 5.4 052/104] XArray: Fix xas_find returning too many entries

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

commit c44aa5e8ab58b5f4cf473970ec784c3333496a2e upstream.

If you call xas_find() with the initial index > max, it should have
returned NULL but was returning the entry at index.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 lib/test_xarray.c |    5 +++++
 lib/xarray.c      |   10 ++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -2,6 +2,7 @@
 /*
  * test_xarray.c: Test the XArray API
  * Copyright (c) 2017-2018 Microsoft Corporation
+ * Copyright (c) 2019-2020 Oracle
  * Author: Matthew Wilcox <willy@xxxxxxxxxxxxx>
  */
 
@@ -911,6 +912,7 @@ static noinline void check_multi_find_1(
 
 	xa_store_order(xa, multi, order, xa_mk_value(multi), GFP_KERNEL);
 	XA_BUG_ON(xa, xa_store_index(xa, next, GFP_KERNEL) != NULL);
+	XA_BUG_ON(xa, xa_store_index(xa, next + 1, GFP_KERNEL) != NULL);
 
 	index = 0;
 	XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
@@ -923,9 +925,12 @@ static noinline void check_multi_find_1(
 	XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT) !=
 			xa_mk_value(next));
 	XA_BUG_ON(xa, index != next);
+	XA_BUG_ON(xa, xa_find_after(xa, &index, next, XA_PRESENT) != NULL);
+	XA_BUG_ON(xa, index != next);
 
 	xa_erase_index(xa, multi);
 	xa_erase_index(xa, next);
+	xa_erase_index(xa, next + 1);
 	XA_BUG_ON(xa, !xa_empty(xa));
 #endif
 }
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1,7 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
  * XArray implementation
- * Copyright (c) 2017 Microsoft Corporation
+ * Copyright (c) 2017-2018 Microsoft Corporation
+ * Copyright (c) 2018-2020 Oracle
  * Author: Matthew Wilcox <willy@xxxxxxxxxxxxx>
  */
 
@@ -1081,6 +1082,8 @@ void *xas_find(struct xa_state *xas, uns
 
 	if (xas_error(xas))
 		return NULL;
+	if (xas->xa_index > max)
+		return set_bounds(xas);
 
 	if (!xas->xa_node) {
 		xas->xa_index = 1;
@@ -1150,6 +1153,8 @@ void *xas_find_marked(struct xa_state *x
 
 	if (xas_error(xas))
 		return NULL;
+	if (xas->xa_index > max)
+		goto max;
 
 	if (!xas->xa_node) {
 		xas->xa_index = 1;
@@ -1867,7 +1872,8 @@ void *xa_find_after(struct xarray *xa, u
 			entry = xas_find_marked(&xas, max, filter);
 		else
 			entry = xas_find(&xas, max);
-		if (xas.xa_node == XAS_BOUNDS)
+
+		if (xas_invalid(&xas))
 			break;
 		if (xas_sibling(&xas))
 			continue;