linux-kernel - [PATCH 4.4 52/86] 9P: Cast to loff

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Date:   Mon,  9 Nov 2020 13:54:59 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Dominique Martinet <asmadeus@...ewreck.org>
Subject: [PATCH 4.4 52/86] 9P: Cast to loff_t before multiplying

From: Matthew Wilcox (Oracle) <willy@...radead.org>

commit f5f7ab168b9a60e12a4b8f2bb6fcc91321dc23c1 upstream.

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

Link: http://lkml.kernel.org/r/20201004180428.14494-2-willy@infradead.org
Cc: stable@...r.kernel.org
Fixes: fb89b45cdfdc ("9P: introduction of a new cache=mmap model.")
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Signed-off-by: Dominique Martinet <asmadeus@...ewreck.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/9p/vfs_file.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -624,9 +624,9 @@ static void v9fs_mmap_vm_close(struct vm
 	struct writeback_control wbc = {
 		.nr_to_write = LONG_MAX,
 		.sync_mode = WB_SYNC_ALL,
-		.range_start = vma->vm_pgoff * PAGE_SIZE,
+		.range_start = (loff_t)vma->vm_pgoff * PAGE_SIZE,
 		 /* absolute end, byte at end included */
-		.range_end = vma->vm_pgoff * PAGE_SIZE +
+		.range_end = (loff_t)vma->vm_pgoff * PAGE_SIZE +
 			(vma->vm_end - vma->vm_start - 1),
 	};