md: use kzalloc() when bitmap is disabled

In drivers/md/md.c get_bitmap_file() uses kmalloc() for creating a
mdu_bitmap_file_t called "file".

5769         file = kmalloc(sizeof(*file), GFP_NOIO);
5770         if (!file)
5771                 return -ENOMEM;

This structure is copied to user space at the end of the function.

5786         if (err == 0 &&
5787             copy_to_user(arg, file, sizeof(*file)))
5788                 err = -EFAULT

But if bitmap is disabled only the first byte of "file" is initialized
with zero, so it's possible to read some bytes (up to 4095) of kernel
space memory from user space. This is an information leak.

5775         /* bitmap disabled, zero the first byte and copy out */
5776         if (!mddev->bitmap_info.file)
5777                 file->pathname[0] = '\0';

Signed-off-by: Benjamin Randazzo <benjamin@randazzo.fr>
Signed-off-by: NeilBrown <neilb@suse.com>
int md_run(struct mddev *mddev)
{
	int err;
	struct md_rdev *rdev;
	struct md_personality *pers;

	if (list_empty(&mddev->disks))
		/* cannot run an array with no devices.. */
		return -EINVAL;

	if (mddev->pers)
		return -EBUSY;
	/* Cannot run until previous stop completes properly */
	if (mddev->sysfs_active)
		return -EBUSY;

	/*
	 * Analyze all RAID superblock(s)
	 */
	if (!mddev->raid_disks) {
		if (!mddev->persistent)
			return -EINVAL;
		analyze_sbs(mddev);
	}

	if (mddev->level != LEVEL_NONE)
		request_module("md-level-%d", mddev->level);
	else if (mddev->clevel[0])
		request_module("md-%s", mddev->clevel);

	/*
	 * Drop all container device buffers, from now on
	 * the only valid external interface is through the md
	 * device.
	 */
	rdev_for_each(rdev, mddev) {
		if (test_bit(Faulty, &rdev->flags))
			continue;
		sync_blockdev(rdev->bdev);
		invalidate_bdev(rdev->bdev);

		/* perform some consistency tests on the device.
		 * We don't want the data to overlap the metadata,
		 * Internal Bitmap issues have been handled elsewhere.
		 */
		if (rdev->meta_bdev) {
			/* Nothing to check */;
		} else if (rdev->data_offset < rdev->sb_start) {
			if (mddev->dev_sectors &&
			    rdev->data_offset + mddev->dev_sectors
			    > rdev->sb_start) {
				printk("md: %s: data overlaps metadata\n",
				       mdname(mddev));
				return -EINVAL;
			}
		} else {
			if (rdev->sb_start + rdev->sb_size/512
			    > rdev->data_offset) {
				printk("md: %s: metadata overlaps data\n",
				       mdname(mddev));
				return -EINVAL;
			}
		}
		sysfs_notify_dirent_safe(rdev->sysfs_state);
	}

	if (mddev->bio_set == NULL)
		mddev->bio_set = bioset_create(BIO_POOL_SIZE, 0);

	spin_lock(&pers_lock);
	pers = find_pers(mddev->level, mddev->clevel);
	if (!pers || !try_module_get(pers->owner)) {
		spin_unlock(&pers_lock);
		if (mddev->level != LEVEL_NONE)
			printk(KERN_WARNING "md: personality for level %d is not loaded!\n",
			       mddev->level);
		else
			printk(KERN_WARNING "md: personality for level %s is not loaded!\n",
			       mddev->clevel);
		return -EINVAL;
	}
	spin_unlock(&pers_lock);
	if (mddev->level != pers->level) {
		mddev->level = pers->level;
		mddev->new_level = pers->level;
	}
	strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));

	if (mddev->reshape_position != MaxSector &&
	    pers->start_reshape == NULL) {
		/* This personality cannot handle reshaping... */
		module_put(pers->owner);
		return -EINVAL;
	}

	if (pers->sync_request) {
		/* Warn if this is a potentially silly
		 * configuration.
		 */
		char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
		struct md_rdev *rdev2;
		int warned = 0;

		rdev_for_each(rdev, mddev)
			rdev_for_each(rdev2, mddev) {
				if (rdev < rdev2 &&
				    rdev->bdev->bd_contains ==
				    rdev2->bdev->bd_contains) {
					printk(KERN_WARNING
					       "%s: WARNING: %s appears to be"
					       " on the same physical disk as"
					       " %s.\n",
					       mdname(mddev),
					       bdevname(rdev->bdev,b),
					       bdevname(rdev2->bdev,b2));
					warned = 1;
				}
			}

		if (warned)
			printk(KERN_WARNING
			       "True protection against single-disk"
			       " failure might be compromised.\n");
	}

	mddev->recovery = 0;
	/* may be over-ridden by personality */
	mddev->resync_max_sectors = mddev->dev_sectors;

	mddev->ok_start_degraded = start_dirty_degraded;

	if (start_readonly && mddev->ro == 0)
		mddev->ro = 2; /* read-only, but switch on first write */

	err = pers->run(mddev);
	if (err)
		printk(KERN_ERR "md: pers->run() failed ...\n");
	else if (pers->size(mddev, 0, 0) < mddev->array_sectors) {
		WARN_ONCE(!mddev->external_size, "%s: default size too small,"
			  " but 'external_size' not in effect?\n", __func__);
		printk(KERN_ERR
		       "md: invalid array_size %llu > default size %llu\n",
		       (unsigned long long)mddev->array_sectors / 2,
		       (unsigned long long)pers->size(mddev, 0, 0) / 2);
		err = -EINVAL;
	}
	if (err == 0 && pers->sync_request &&
	    (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
		struct bitmap *bitmap;

		bitmap = bitmap_create(mddev, -1);
		if (IS_ERR(bitmap)) {
			err = PTR_ERR(bitmap);
			printk(KERN_ERR "%s: failed to create bitmap (%d)\n",
			       mdname(mddev), err);
		} else
			mddev->bitmap = bitmap;

	}
	if (err) {
		mddev_detach(mddev);
		if (mddev->private)
			pers->free(mddev, mddev->private);
		mddev->private = NULL;
		module_put(pers->owner);
		bitmap_destroy(mddev);
		return err;
	}
	if (mddev->queue) {
		mddev->queue->backing_dev_info.congested_data = mddev;
		mddev->queue->backing_dev_info.congested_fn = md_congested;
		blk_queue_merge_bvec(mddev->queue, md_mergeable_bvec);
	}
	if (pers->sync_request) {
		if (mddev->kobj.sd &&
		    sysfs_create_group(&mddev->kobj, &md_redundancy_group))
			printk(KERN_WARNING
			       "md: cannot register extra attributes for %s\n",
			       mdname(mddev));
		mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
	} else if (mddev->ro == 2) /* auto-readonly not meaningful */
		mddev->ro = 0;

	atomic_set(&mddev->writes_pending,0);
	atomic_set(&mddev->max_corr_read_errors,
		   MD_DEFAULT_MAX_CORRECTED_READ_ERRORS);
	mddev->safemode = 0;
	mddev->safemode_timer.function = md_safemode_timeout;
	mddev->safemode_timer.data = (unsigned long) mddev;
	mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */
	mddev->in_sync = 1;
	smp_wmb();
	spin_lock(&mddev->lock);
	mddev->pers = pers;
	mddev->ready = 1;
	spin_unlock(&mddev->lock);
	rdev_for_each(rdev, mddev)
		if (rdev->raid_disk >= 0)
			if (sysfs_link_rdev(mddev, rdev))
				/* failure here is OK */;

	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);

	if (mddev->flags & MD_UPDATE_SB_FLAGS)
		md_update_sb(mddev, 0);

	md_new_event(mddev);
	sysfs_notify_dirent_safe(mddev->sysfs_state);
	sysfs_notify_dirent_safe(mddev->sysfs_action);
	sysfs_notify(&mddev->kobj, NULL, "degraded");
	return 0;
}

int md_run(struct mddev *mddev)
{
	int err;
	struct md_rdev *rdev;
	struct md_personality *pers;

	if (list_empty(&mddev->disks))
		/* cannot run an array with no devices.. */
		return -EINVAL;

	if (mddev->pers)
		return -EBUSY;
	/* Cannot run until previous stop completes properly */
	if (mddev->sysfs_active)
		return -EBUSY;

	/*
	 * Analyze all RAID superblock(s)
	 */
	if (!mddev->raid_disks) {
		if (!mddev->persistent)
			return -EINVAL;
		analyze_sbs(mddev);
	}

	if (mddev->level != LEVEL_NONE)
		request_module("md-level-%d", mddev->level);
	else if (mddev->clevel[0])
		request_module("md-%s", mddev->clevel);

	/*
	 * Drop all container device buffers, from now on
	 * the only valid external interface is through the md
	 * device.
	 */
	rdev_for_each(rdev, mddev) {
		if (test_bit(Faulty, &rdev->flags))
			continue;
		sync_blockdev(rdev->bdev);
		invalidate_bdev(rdev->bdev);

		/* perform some consistency tests on the device.
		 * We don't want the data to overlap the metadata,
		 * Internal Bitmap issues have been handled elsewhere.
		 */
		if (rdev->meta_bdev) {
			/* Nothing to check */;
		} else if (rdev->data_offset < rdev->sb_start) {
			if (mddev->dev_sectors &&
			    rdev->data_offset + mddev->dev_sectors
			    > rdev->sb_start) {
				printk("md: %s: data overlaps metadata\n",
				       mdname(mddev));
				return -EINVAL;
			}
		} else {
			if (rdev->sb_start + rdev->sb_size/512
			    > rdev->data_offset) {
				printk("md: %s: metadata overlaps data\n",
				       mdname(mddev));
				return -EINVAL;
			}
		}
		sysfs_notify_dirent_safe(rdev->sysfs_state);
	}

	if (mddev->bio_set == NULL)
		mddev->bio_set = bioset_create(BIO_POOL_SIZE, 0);

	spin_lock(&pers_lock);
	pers = find_pers(mddev->level, mddev->clevel);
	if (!pers || !try_module_get(pers->owner)) {
		spin_unlock(&pers_lock);
		if (mddev->level != LEVEL_NONE)
			printk(KERN_WARNING "md: personality for level %d is not loaded!\n",
			       mddev->level);
		else
			printk(KERN_WARNING "md: personality for level %s is not loaded!\n",
			       mddev->clevel);
		return -EINVAL;
	}
	spin_unlock(&pers_lock);
	if (mddev->level != pers->level) {
		mddev->level = pers->level;
		mddev->new_level = pers->level;
	}
	strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));

	if (mddev->reshape_position != MaxSector &&
	    pers->start_reshape == NULL) {
		/* This personality cannot handle reshaping... */
		module_put(pers->owner);
		return -EINVAL;
	}

	if (pers->sync_request) {
		/* Warn if this is a potentially silly
		 * configuration.
		 */
		char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
		struct md_rdev *rdev2;
		int warned = 0;

		rdev_for_each(rdev, mddev)
			rdev_for_each(rdev2, mddev) {
				if (rdev < rdev2 &&
				    rdev->bdev->bd_contains ==
				    rdev2->bdev->bd_contains) {
					printk(KERN_WARNING
					       "%s: WARNING: %s appears to be"
					       " on the same physical disk as"
					       " %s.\n",
					       mdname(mddev),
					       bdevname(rdev->bdev,b),
					       bdevname(rdev2->bdev,b2));
					warned = 1;
				}
			}

		if (warned)
			printk(KERN_WARNING
			       "True protection against single-disk"
			       " failure might be compromised.\n");
	}

	mddev->recovery = 0;
	/* may be over-ridden by personality */
	mddev->resync_max_sectors = mddev->dev_sectors;

	mddev->ok_start_degraded = start_dirty_degraded;

	if (start_readonly && mddev->ro == 0)
		mddev->ro = 2; /* read-only, but switch on first write */

	err = pers->run(mddev);
	if (err)
		printk(KERN_ERR "md: pers->run() failed ...\n");
	else if (pers->size(mddev, 0, 0) < mddev->array_sectors) {
		WARN_ONCE(!mddev->external_size, "%s: default size too small,"
			  " but 'external_size' not in effect?\n", __func__);
		printk(KERN_ERR
		       "md: invalid array_size %llu > default size %llu\n",
		       (unsigned long long)mddev->array_sectors / 2,
		       (unsigned long long)pers->size(mddev, 0, 0) / 2);
		err = -EINVAL;
	}
	if (err == 0 && pers->sync_request &&
	    (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
		struct bitmap *bitmap;

		bitmap = bitmap_create(mddev, -1);
		if (IS_ERR(bitmap)) {
			err = PTR_ERR(bitmap);
			printk(KERN_ERR "%s: failed to create bitmap (%d)\n",
			       mdname(mddev), err);
		} else
			mddev->bitmap = bitmap;

	}
	if (err) {
		mddev_detach(mddev);
		if (mddev->private)
			pers->free(mddev, mddev->private);
		mddev->private = NULL;
		module_put(pers->owner);
		bitmap_destroy(mddev);
		return err;
	}
	if (mddev->queue) {
		mddev->queue->backing_dev_info.congested_data = mddev;
		mddev->queue->backing_dev_info.congested_fn = md_congested;
		blk_queue_merge_bvec(mddev->queue, md_mergeable_bvec);
	}
	if (pers->sync_request) {
		if (mddev->kobj.sd &&
		    sysfs_create_group(&mddev->kobj, &md_redundancy_group))
			printk(KERN_WARNING
			       "md: cannot register extra attributes for %s\n",
			       mdname(mddev));
		mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
	} else if (mddev->ro == 2) /* auto-readonly not meaningful */
		mddev->ro = 0;

	atomic_set(&mddev->writes_pending,0);
	atomic_set(&mddev->max_corr_read_errors,
		   MD_DEFAULT_MAX_CORRECTED_READ_ERRORS);
	mddev->safemode = 0;
	mddev->safemode_timer.function = md_safemode_timeout;
	mddev->safemode_timer.data = (unsigned long) mddev;
	mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */
	mddev->in_sync = 1;
	smp_wmb();
	spin_lock(&mddev->lock);
	mddev->pers = pers;
	mddev->ready = 1;
	spin_unlock(&mddev->lock);
	rdev_for_each(rdev, mddev)
		if (rdev->raid_disk >= 0)
			if (sysfs_link_rdev(mddev, rdev))
				/* failure here is OK */;

	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);

	if (mddev->flags & MD_UPDATE_SB_FLAGS)
		md_update_sb(mddev, 0);

	md_new_event(mddev);
	sysfs_notify_dirent_safe(mddev->sysfs_state);
	sysfs_notify_dirent_safe(mddev->sysfs_action);
	sysfs_notify(&mddev->kobj, NULL, "degraded");
	return 0;
}
