[GIT PULL] SCSI fixes for 4.3-rc4

From: James Bottomley
Date: Fri Oct 30 2015 - 23:39:52 EST

This is three essential bug fixes for various SCSI parts. The only
affected users are SCSI multi-path via device handler (basically all the
enterprise) and mvsas users. The dh bugs are an async entanglement in
boot resulting in a serious WARN_ON trip and a use after free on remove
leading to a crash with strict memory accounting. The mvsas bug
manifests as a null deref oops but only on abort sequences; however,
these can commonly occur with SATA attached devices, hence the fix.

The patch is available here:

git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi.git scsi-fixes

The short changelog is:

Christoph Hellwig (1):
scsi_dh: don't try to load a device handler during async probing

DÄvis MosÄns (1):
mvsas: Fix NULL pointer dereference in mvs_slot_task_free

Junichi Nomura (1):
scsi_dh: fix use-after-free when removing scsi device

And the diffstat:

drivers/scsi/mvsas/mv_sas.c | 2 ++
drivers/scsi/scsi_dh.c | 8 ++++++--
drivers/scsi/scsi_priv.h | 2 ++
drivers/scsi/scsi_sysfs.c | 2 ++
4 files changed, 12 insertions(+), 2 deletions(-)

With full diff below.



diff --git a/drivers/scsi/mvsas/mv_sas.c b/drivers/scsi/mvsas/mv_sas.c
index 454536c..9c78074 100644
--- a/drivers/scsi/mvsas/mv_sas.c
+++ b/drivers/scsi/mvsas/mv_sas.c
@@ -887,6 +887,8 @@ static void mvs_slot_free(struct mvs_info *mvi, u32 rx_desc)
static void mvs_slot_task_free(struct mvs_info *mvi, struct sas_task *task,
struct mvs_slot_info *slot, u32 slot_idx)
+ if (!slot)
+ return;
if (!slot->task)
if (!sas_protocol_ata(task->task_proto))
diff --git a/drivers/scsi/scsi_dh.c b/drivers/scsi/scsi_dh.c
index 0a2168e..e7649ed 100644
--- a/drivers/scsi/scsi_dh.c
+++ b/drivers/scsi/scsi_dh.c
@@ -226,16 +226,20 @@ int scsi_dh_add_device(struct scsi_device *sdev)

drv = scsi_dh_find_driver(sdev);
if (drv)
- devinfo = scsi_dh_lookup(drv);
+ devinfo = __scsi_dh_lookup(drv);
if (devinfo)
err = scsi_dh_handler_attach(sdev, devinfo);
return err;

-void scsi_dh_remove_device(struct scsi_device *sdev)
+void scsi_dh_release_device(struct scsi_device *sdev)
if (sdev->handler)
+void scsi_dh_remove_device(struct scsi_device *sdev)
device_remove_file(&sdev->sdev_gendev, &scsi_dh_state_attr);

diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index 644bb73..4d01cdb 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -173,9 +173,11 @@ extern struct async_domain scsi_sd_probe_domain;
/* scsi_dh.c */
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);
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) { }

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index b333389..dff8faf 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -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);

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