[PATCH 6.1 259/280] iomap: Fix possible overflow condition in iomap_write_delalloc_scan

Greg Kroah-Hartman
2026-02-04T15:17:41Z

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

[ 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@infradead.org>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Rajani Kantha <681739313@139.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/iomap/buffered-io.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -903,7 +903,7 @@ static int iomap_write_delalloc_scan(str
* 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 */