9P: Cast to loff_t before multiplying

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@vger.kernel.org
Fixes: fb89b45cdfdc ("9P: introduction of a new cache=mmap model.")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 3576123d82990e61dca4b3bbc8dabb1ebd0cea6a..6d97b6b4d34b6adcefef4c7e2cc714bcb87e792d 100644 (file)
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -612,9 +612,9 @@ static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
        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),
        };