[PATCH] md: fix potential NULL pointer dereference in md_super_write

[Ye Chey <yechey@xxxxxxxxxxx>]

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@xxxxxxxxxxx>
---
 drivers/md/md.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9daa78c5f..492cbc1c7 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1002,6 +1002,9 @@ 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