FAILED: patch "[PATCH] md/raid10: fix null-ptr-deref in raid10_sync_request" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.14.y
git checkout FETCH_HEAD
git cherry-pick -x a405c6f0229526160aa3f177f65e20c86fce84c5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023050703-eldercare-flattery-36cb@gregkh' --subject-prefix 'PATCH 4.14.y' HEAD^..

Possible dependencies:

a405c6f02295 ("md/raid10: fix null-ptr-deref in raid10_sync_request") afeee514ce7f ("md: convert to bioset_init()/mempool_init()") b126194cbb79 ("MD: Free bioset when md_run fails")
1532d9e87e8b ("raid5-ppl: PPL support for disks with write-back cache enabled") 0202ce8a90ef ("md: release allocated bitset sync_set") b03e0ccb5ab9 ("md: remove special meaning of ->quiesce(.., 2)") 9e1cc0a54556 ("md: use mddev_suspend/resume instead of ->quiesce()") b3143b9a38d5 ("md: move suspend_hi/lo handling into core md code") 52a0d49de3d5 ("md: don't call bitmap_create() while array is quiesced.") 385f4d7f946b ("md-cluster: fix wrong condition check in raid1_write_request")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a405c6f0229526160aa3f177f65e20c86fce84c5 Mon Sep 17 00:00:00 2001
From: Li Nan <[email protected]>
Date: Wed, 22 Feb 2023 12:10:00 +0800
Subject: [PATCH] md/raid10: fix null-ptr-deref in raid10_sync_request

init_resync() inits mempool and sets conf->have_replacemnt at the beginning of sync, close_sync() frees the mempool when sync is completed.

After [1] recovery might be skipped and init_resync() is called but close_sync() is not. null-ptr-deref occurs with r10bio->dev[i].repl_bio.

The following is one way to reproduce the issue.

1) create a array, wait for resync to complete, mddev->recovery_cp is set to MaxSector.
2) recovery is woken and it is skipped. conf->have_replacement is set to 0 in init_resync(). close_sync() not called.
3) some io errors and rdev A is set to WantReplacement.
4) a new device is added and set to A's replacement.
5) recovery is woken, A have replacement, but conf->have_replacemnt is
0. r10bio->dev[i].repl_bio will not be alloced and null-ptr-deref occurs.

Fix it by not calling init_resync() if recovery skipped.

[1] commit 7e83ccbecd60 ("md/raid10: Allow skipping recovery when clean arrays are assembled")

index db9ee3b637d6..9e0e7bf524aa 100644
@@ -3297,10 +3297,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 	sector_t chunk_mask = conf->geo.chunk_mask;
 	int page_idx = 0;
 
-	if (!mempool_initialized(&conf->r10buf_pool))
-		if (init_resync(conf))
-			return 0;
-
 	/*
 	 * Allow skipping a full rebuild for incremental assembly
 	 * of a clean array, like RAID1 does.

@@ -3316,6 +3312,10 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 		return mddev->dev_sectors - sector_nr;
 	}
 
+	if (!mempool_initialized(&conf->r10buf_pool))
+		if (init_resync(conf))
+			return 0;
+
  skipped:
 	max_sector = mddev->dev_sectors;
 	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||