From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Tue, 13 Oct 2020 12:46:29 +0000 (-0400)
Subject: XArray: Fix xas_create_range for ranges above 4 billion
X-Git-Tag: xarray-5.9^0
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=84c34df158cf215b0cd1475ab3b8e6f212f81f23;p=users%2Fwilly%2Fxarray.git

XArray: Fix xas_create_range for ranges above 4 billion

The 'sibs' variable would be shifted as a 32-bit integer, so if 'shift'
is more than 32, this is undefined behaviour.  In practice, this doesn't
happen because the page cache is the only user and nobody uses 16TB pages.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---

diff --git a/lib/xarray.c b/lib/xarray.c
index 1fa5c5658e63..2046d676ab41 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -703,7 +703,7 @@ void xas_create_range(struct xa_state *xas)
 	unsigned char shift = xas->xa_shift;
 	unsigned char sibs = xas->xa_sibs;
 
-	xas->xa_index |= ((sibs + 1) << shift) - 1;
+	xas->xa_index |= ((sibs + 1UL) << shift) - 1;
 	if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
 		xas->xa_offset |= sibs;
 	xas->xa_shift = 0;