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[SCSI] sg: checking sdp->detached isn't protected when open 

@detached is set under the protection of sg_index_lock. Without getting the
lock, new sfp will be added during sg removal and there is no chance for it
to be picked out. So check with sg_index_lock held in sg_add_sfp().

Signed-off-by: Vaughan Cao <vaughan.cao@oracle.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Vaughan Cao 2013-08-29 10:00:38 +08:00 committed by James Bottomley
parent 00b2d9d6d0
commit e32c9e6300
1 changed files with 9 additions and 8 deletions
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17
drivers/scsi/sg.c
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@ -295,23 +295,20 @@ sg_open(struct inode *inode, struct file *filp)
if (flags & O_EXCL)
sdp->exclude = 1; /* used by release lock */
if (sdp->detached) {
retval = -ENODEV;
goto sem_out;
}
if (sfds_list_empty(sdp)) { /* no existing opens on this device */
sdp->sgdebug = 0;
q = sdp->device->request_queue;
sdp->sg_tablesize = queue_max_segments(q);
}
if ((sfp = sg_add_sfp(sdp, dev)))
sfp = sg_add_sfp(sdp, dev);
if (!IS_ERR(sfp))
filp->private_data = sfp;
/* retval is already provably zero at this point because of the
* check after retval = scsi_autopm_get_device(sdp->device))
*/
else {
retval = -ENOMEM;
sem_out:
retval = PTR_ERR(sfp);
if (flags & O_EXCL) {
sdp->exclude = 0; /* undo if error */
up_write(&sdp->o_sem);
@ -2045,7 +2042,7 @@ sg_add_sfp(Sg_device * sdp, int dev)
sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN);
if (!sfp)
return NULL;
return ERR_PTR(-ENOMEM);
init_waitqueue_head(&sfp->read_wait);
rwlock_init(&sfp->rq_list_lock);
@ -2060,6 +2057,10 @@ sg_add_sfp(Sg_device * sdp, int dev)
sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
sfp->parentdp = sdp;
write_lock_irqsave(&sg_index_lock, iflags);
if (sdp->detached) {
write_unlock_irqrestore(&sg_index_lock, iflags);
return ERR_PTR(-ENODEV);
}
list_add_tail(&sfp->sfd_siblings, &sdp->sfds);
write_unlock_irqrestore(&sg_index_lock, iflags);
SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp));