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Commit fe316bf2 authored by Jun'ichi Nomura's avatar Jun'ichi Nomura Committed by Jens Axboe
Browse files

block: Fix NULL pointer dereference in sd_revalidate_disk 

Since 2.6.39 (1196f8b8), when a driver returns -ENOMEDIUM for open(),
__blkdev_get() calls rescan_partitions() to remove
in-kernel partition structures and raise KOBJ_CHANGE uevent.

However it ends up calling driver's revalidate_disk without open
and could cause oops.

In the case of SCSI:

  process A                  process B
  ----------------------------------------------
  sys_open
    __blkdev_get
      sd_open
        returns -ENOMEDIUM
                             scsi_remove_device
                               <scsi_device torn down>
      rescan_partitions
        sd_revalidate_disk
          <oops>
Oopses are reported here:
http://marc.info/?l=linux-scsi&m=132388619710052



This patch separates the partition invalidation from rescan_partitions()
and use it for -ENOMEDIUM case.

Reported-by: default avatarHuajun Li <huajun.li.lee@gmail.com>
Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Cc: stable@kernel.org
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 621032ad

block/partition-generic.c

+40 −8
Original line number Diff line number Diff line
@@ -389,17 +389,11 @@ static bool disk_unlock_native_capacity(struct gendisk *disk) 
	}

}



int rescan_partitions(struct gendisk *disk, struct block_device *bdev)

static int drop_partitions(struct gendisk *disk, struct block_device *bdev)

{

	struct parsed_partitions *state = NULL;

	struct disk_part_iter piter;

	struct hd_struct *part;

	int p, highest, res;

rescan:

	if (state && !IS_ERR(state)) {

		kfree(state);

		state = NULL;

	}

	int res;



	if (bdev->bd_part_count)

		return -EBUSY;
@@ -412,6 +406,24 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev) 
		delete_partition(disk, part->partno);

	disk_part_iter_exit(&piter);



	return 0;

}



int rescan_partitions(struct gendisk *disk, struct block_device *bdev)

{

	struct parsed_partitions *state = NULL;

	struct hd_struct *part;

	int p, highest, res;

rescan:

	if (state && !IS_ERR(state)) {

		kfree(state);

		state = NULL;

	}



	res = drop_partitions(disk, bdev);

	if (res)

		return res;



	if (disk->fops->revalidate_disk)

		disk->fops->revalidate_disk(disk);

	check_disk_size_change(disk, bdev);
@@ -515,6 +527,26 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev) 
	return 0;

}



int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)

{

	int res;



	if (!bdev->bd_invalidated)

		return 0;



	res = drop_partitions(disk, bdev);

	if (res)

		return res;



	set_capacity(disk, 0);

	check_disk_size_change(disk, bdev);

	bdev->bd_invalidated = 0;

	/* tell userspace that the media / partition table may have changed */

	kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);



	return 0;

}



unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)

{

	struct address_space *mapping = bdev->bd_inode->i_mapping;

fs/block_dev.c

+12 −4
Original line number Diff line number Diff line
@@ -1183,8 +1183,12 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) 
			 * The latter is necessary to prevent ghost

			 * partitions on a removed medium.

			 */

			if (bdev->bd_invalidated && (!ret || ret == -ENOMEDIUM))

			if (bdev->bd_invalidated) {

				if (!ret)

					rescan_partitions(disk, bdev);

				else if (ret == -ENOMEDIUM)

					invalidate_partitions(disk, bdev);

			}

			if (ret)

				goto out_clear;

		} else {
@@ -1214,8 +1218,12 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) 
			if (bdev->bd_disk->fops->open)

				ret = bdev->bd_disk->fops->open(bdev, mode);

			/* the same as first opener case, read comment there */

			if (bdev->bd_invalidated && (!ret || ret == -ENOMEDIUM))

			if (bdev->bd_invalidated) {

				if (!ret)

					rescan_partitions(bdev->bd_disk, bdev);

				else if (ret == -ENOMEDIUM)

					invalidate_partitions(bdev->bd_disk, bdev);

			}

			if (ret)

				goto out_unlock_bdev;

		}

include/linux/genhd.h

+1 −0
Original line number Diff line number Diff line
@@ -596,6 +596,7 @@ extern char *disk_name (struct gendisk *hd, int partno, char *buf); 


extern int disk_expand_part_tbl(struct gendisk *disk, int target);

extern int rescan_partitions(struct gendisk *disk, struct block_device *bdev);

extern int invalidate_partitions(struct gendisk *disk, struct block_device *bdev);

extern struct hd_struct * __must_check add_partition(struct gendisk *disk,

						     int partno, sector_t start,

						     sector_t len, int flags,