linux-kernel - [PATCH] iomap: fix potential NULL pointer dereference in iomap_alloc

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Message-ID: <20250523091417.2825-1-yechey@ai-sast.com>
Date: Fri, 23 May 2025 17:14:17 +0800
From: Ye Chey <yechey@...sast.com>
To: brauner@...nel.org,
	djwong@...nel.org
Cc: linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Ye Chey <yechey@...sast.com>
Subject: [PATCH] iomap: fix potential NULL pointer dereference in iomap_alloc_ioend

Under memory pressure, bio_alloc_bioset() may fail and return NULL. Add
a check to prevent NULL pointer dereference in iomap_alloc_ioend().
This could happen when the system is under memory pressure and the
allocation of the bio structure fails.

Signed-off-by: Ye Chey <yechey@...sast.com>
---
 fs/iomap/buffered-io.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 5b08bd417..d243b191e 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1618,6 +1618,8 @@ static struct iomap_ioend *iomap_alloc_ioend(struct iomap_writepage_ctx *wpc,
 	bio = bio_alloc_bioset(wpc->iomap.bdev, BIO_MAX_VECS,
 			       REQ_OP_WRITE | wbc_to_write_flags(wbc),
 			       GFP_NOFS, &iomap_ioend_bioset);
+	if (!bio)
+		return NULL;
 	bio->bi_iter.bi_sector = iomap_sector(&wpc->iomap, pos);
 	bio->bi_end_io = iomap_writepage_end_bio;
 	bio->bi_write_hint = inode->i_write_hint;
-- 
2.44.0