[PATCH 1/2] Crash in linux kernel when disconnecting usb storage

From: Denis V. Lunev
Date: Tue Nov 03 2009 - 04:52:47 EST

From: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>

__scsi_remove_device() in scsi_forget_host() is executed out of scan_mutex
and races with scsi_destroy_sdev() <- scsi_sysfs_add_devices()
<- scsi_finish_async_scan(). The result is use after free and/or
double free, oops.

The fix is simple, move scsi_forget_host() under scan_mutex.

scsi_forget_host() is just sequence of __scsi_remove_device().
All another calls of __scsi_remove_device() are made under scan_mutex.
So that it is safe.

Signed-off-by: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
CC: James E.J. Bottomley <James.Bottomley@xxxxxxx>
Signed-off-by: Denis V. Lunev <den@xxxxxxxxxx>
drivers/scsi/hosts.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 5fd2da4..c968cc3 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -164,8 +164,8 @@ void scsi_remove_host(struct Scsi_Host *shost)
spin_unlock_irqrestore(shost->host_lock, flags);
- mutex_unlock(&shost->scan_mutex);
+ mutex_unlock(&shost->scan_mutex);

spin_lock_irqsave(shost->host_lock, flags);

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