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Commit 38d33593 authored by Li Nan's avatar Li Nan Committed by Greg Kroah-Hartman
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md/raid10: fix null-ptr-deref in raid10_sync_request 



commit a405c6f0229526160aa3f177f65e20c86fce84c5 upstream.

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 7e83ccbe ("md/raid10: Allow skipping recovery when clean arrays are assembled")
Fixes: 7e83ccbe ("md/raid10: Allow skipping recovery when clean arrays are assembled")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarLi Nan <linan122@huawei.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230222041000.3341651-3-linan666@huaweicloud.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d536f997

drivers/md/raid10.c

+4 −4
Original line number Diff line number Diff line
@@ -2957,10 +2957,6 @@ 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.
@@ -2976,6 +2972,10 @@ 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) ||