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Commit 23695e41 authored by Junichi Nomura's avatar Junichi Nomura Committed by James Bottomley
Browse files

scsi_dh: fix use-after-free when removing scsi device 



The commit 1bab0de0 ("dm-mpath, scsi_dh: don't let dm detach device
handlers") removed reference counting of attached scsi device handler.
As a result, handler data is freed immediately via scsi_dh->detach()
in the context of scsi_remove_device() where activation request can be
still in flight.

This patch moves scsi_dh_handler_detach() to sdev releasing function,
scsi_device_dev_release_usercontext(), at that point the device
is already in quiesced state.

Fixes: 1bab0de0 ("dm-mpath, scsi_dh: don't let dm detach device handlers")
Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJames Bottomley <JBottomley@Odin.com>
parent 22805217

drivers/scsi/scsi_dh.c

+5 −1
Original line number Diff line number Diff line
@@ -232,10 +232,14 @@ int scsi_dh_add_device(struct scsi_device *sdev) 
	return err;

}



void scsi_dh_remove_device(struct scsi_device *sdev)

void scsi_dh_release_device(struct scsi_device *sdev)

{

	if (sdev->handler)

		scsi_dh_handler_detach(sdev);

}



void scsi_dh_remove_device(struct scsi_device *sdev)

{

	device_remove_file(&sdev->sdev_gendev, &scsi_dh_state_attr);

}

drivers/scsi/scsi_priv.h

+2 −0
Original line number Diff line number Diff line
@@ -173,9 +173,11 @@ extern struct async_domain scsi_sd_probe_domain; 
/* scsi_dh.c */

#ifdef CONFIG_SCSI_DH

int scsi_dh_add_device(struct scsi_device *sdev);

void scsi_dh_release_device(struct scsi_device *sdev);

void scsi_dh_remove_device(struct scsi_device *sdev);

#else

static inline int scsi_dh_add_device(struct scsi_device *sdev) { return 0; }

static inline void scsi_dh_release_device(struct scsi_device *sdev) { }

static inline void scsi_dh_remove_device(struct scsi_device *sdev) { }

#endif

drivers/scsi/scsi_sysfs.c

+2 −0
Original line number Diff line number Diff line
@@ -399,6 +399,8 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work) 


	sdev = container_of(work, struct scsi_device, ew.work);



	scsi_dh_release_device(sdev);



	parent = sdev->sdev_gendev.parent;



	spin_lock_irqsave(sdev->host->host_lock, flags);