[PATCH 4.14 104/125] 9P: Cast to loff_t before multiplying

Greg Kroah-Hartman
2020-11-03T21:13:28Z

From: Matthew Wilcox (Oracle) <willy@infradead.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@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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),
};