linux-kernel - [PATCH 2/7] buffer: Promote to unsigned long long before shifting

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Date:   Sun,  4 Oct 2020 19:04:23 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>, ericvh@...il.com,
        lucho@...kov.net, viro@...iv.linux.org.uk, jlayton@...nel.org,
        idryomov@...il.com, mark@...heh.com, jlbec@...lplan.org,
        joseph.qi@...ux.alibaba.com, v9fs-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, ceph-devel@...r.kernel.org,
        ocfs2-devel@....oracle.com, linux-btrfs@...r.kernel.org,
        clm@...com, josef@...icpanda.com, dsterba@...e.com,
        stable@...r.kernel.org
Subject: [PATCH 2/7] buffer: Promote to unsigned long long before shifting

On 32-bit systems, this shift will overflow for files larger than 4GB.

Cc: stable@...r.kernel.org
Fixes: 5417169026c3 ("[FS] Implement block_page_mkwrite.")
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 fs/buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 50bbc99e3d96..66f4765e60ee 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2515,7 +2515,7 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
 	}
 
 	/* page is wholly or partially inside EOF */
-	if (((page->index + 1) << PAGE_SHIFT) > size)
+	if (((page->index + 1ULL) << PAGE_SHIFT) > size)
 		end = size & ~PAGE_MASK;
 	else
 		end = PAGE_SIZE;
-- 
2.28.0