[PATCH AUTOSEL 6.5 1/6] iomap: Fix possible overflow condition in iomap_write_delalloc_scan

[Sasha Levin]

From: "Ritesh Harjani (IBM)" <ritesh.list@xxxxxxxxx>

[ Upstream commit eee2d2e6ea5550118170dbd5bb1316ceb38455fb ]

folio_next_index() returns an unsigned long value which left shifted
by PAGE_SHIFT could possibly cause an overflow on 32-bit system. Instead
use folio_pos(folio) + folio_size(folio), which does this correctly.

Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/iomap/buffered-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index aa8967cca1a31..4dc4bbc4be10a 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -932,7 +932,7 @@ static int iomap_write_delalloc_scan(struct inode *inode,
 			 * the end of this data range, not the end of the folio.
 			 */
 			*punch_start_byte = min_t(loff_t, end_byte,
-					folio_next_index(folio) << PAGE_SHIFT);
+					folio_pos(folio) + folio_size(folio));
 		}
 
 		/* move offset to start of next folio in range */
-- 
2.40.1