linux-kernel - [PATCH] md: fix potential NULL pointer dereference in md_super

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Message-ID: <20250523093554.23182-1-yechey@ai-sast.com>
Date: Fri, 23 May 2025 17:35:54 +0800
From: Ye Chey <yechey@...sast.com>
To: song@...nel.org,
	yukuai3@...wei.com
Cc: linux-raid@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Ye Chey <yechey@...sast.com>
Subject: [PATCH] md: fix potential NULL pointer dereference in md_super_write

The bio_alloc_bioset() call in md_super_write() could fail under memory
pressure and return NULL. Add a check to handle this case gracefully by
returning early, preventing a potential NULL pointer dereference.

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

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9daa78c5f..a0e2d90d4 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1002,6 +1002,8 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 			      REQ_OP_WRITE | REQ_SYNC | REQ_IDLE | REQ_META
 				  | REQ_PREFLUSH | REQ_FUA,
 			      GFP_NOIO, &mddev->sync_set);
+	if (!bio)
+		return;
 
 	atomic_inc(&rdev->nr_pending);
 
-- 
2.44.0