linux-kernel - [PATCH 6.6.y] iomap: Fix possible overflow condition in iomap_write_delalloc

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Message-Id: <20260122033826.3110454-1-681739313@139.com>
Date: Thu, 22 Jan 2026 11:38:26 +0800
From: Rajani Kantha <681739313@....com>
To: gregkh@...uxfoundation.org,
	stable@...r.kernel.org,
	ritesh.list@...il.com
Cc: patches@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	willy@...radead.org,
	djwong@...nel.org,
	hch@...radead.org,
	linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: [PATCH 6.6.y] iomap: Fix possible overflow condition in iomap_write_delalloc_scan

From: "Ritesh Harjani (IBM)" <ritesh.list@...il.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@...radead.org>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>
Reviewed-by: Darrick J. Wong <djwong@...nel.org>
Signed-off-by: Rajani Kantha <681739313@....com>
---
 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 70e246f7e8fe..e4f58d1e12d4 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -903,7 +903,7 @@ 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 */
-- 
2.34.1