Commit 2e6edc95 authored by Dan Williams's avatar Dan Williams
Browse files

block: protect rw_page against device teardown 



Fix use after free crashes like the following:

 general protection fault: 0000 [#1] SMP
 Call Trace:
  [<ffffffffa0050216>] ? pmem_do_bvec.isra.12+0xa6/0xf0 [nd_pmem]
  [<ffffffffa0050ba2>] pmem_rw_page+0x42/0x80 [nd_pmem]
  [<ffffffff8128fd90>] bdev_read_page+0x50/0x60
  [<ffffffff812972f0>] do_mpage_readpage+0x510/0x770
  [<ffffffff8128fd20>] ? I_BDEV+0x20/0x20
  [<ffffffff811d86dc>] ? lru_cache_add+0x1c/0x50
  [<ffffffff81297657>] mpage_readpages+0x107/0x170
  [<ffffffff8128fd20>] ? I_BDEV+0x20/0x20
  [<ffffffff8128fd20>] ? I_BDEV+0x20/0x20
  [<ffffffff8129058d>] blkdev_readpages+0x1d/0x20
  [<ffffffff811d615f>] __do_page_cache_readahead+0x28f/0x310
  [<ffffffff811d6039>] ? __do_page_cache_readahead+0x169/0x310
  [<ffffffff811c5abd>] ? pagecache_get_page+0x2d/0x1d0
  [<ffffffff811c76f6>] filemap_fault+0x396/0x530
  [<ffffffff811f816e>] __do_fault+0x4e/0xf0
  [<ffffffff811fce7d>] handle_mm_fault+0x11bd/0x1b50

Cc: <stable@vger.kernel.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Reported-by: default avatarkbuild test robot <lkp@intel.com>
Acked-by: default avatarMatthew Wilcox <willy@linux.intel.com>
[willy: symmetry fixups]
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 0df9d41a

block/blk.h

+0 −2
Original line number Diff line number Diff line
@@ -72,8 +72,6 @@ void blk_dequeue_request(struct request *rq); 
void __blk_queue_free_tags(struct request_queue *q);

bool __blk_end_bidi_request(struct request *rq, int error,

			    unsigned int nr_bytes, unsigned int bidi_bytes);

int blk_queue_enter(struct request_queue *q, gfp_t gfp);

void blk_queue_exit(struct request_queue *q);

void blk_freeze_queue(struct request_queue *q);



static inline void blk_queue_enter_live(struct request_queue *q)

fs/block_dev.c

+16 −2
Original line number Diff line number Diff line
@@ -390,9 +390,17 @@ int bdev_read_page(struct block_device *bdev, sector_t sector, 
			struct page *page)

{

	const struct block_device_operations *ops = bdev->bd_disk->fops;

	int result = -EOPNOTSUPP;



	if (!ops->rw_page || bdev_get_integrity(bdev))

		return -EOPNOTSUPP;

	return ops->rw_page(bdev, sector + get_start_sect(bdev), page, READ);

		return result;



	result = blk_queue_enter(bdev->bd_queue, GFP_KERNEL);

	if (result)

		return result;

	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, READ);

	blk_queue_exit(bdev->bd_queue);

	return result;

}

EXPORT_SYMBOL_GPL(bdev_read_page);
@@ -421,14 +429,20 @@ int bdev_write_page(struct block_device *bdev, sector_t sector, 
	int result;

	int rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE;

	const struct block_device_operations *ops = bdev->bd_disk->fops;



	if (!ops->rw_page || bdev_get_integrity(bdev))

		return -EOPNOTSUPP;

	result = blk_queue_enter(bdev->bd_queue, GFP_KERNEL);

	if (result)

		return result;



	set_page_writeback(page);

	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, rw);

	if (result)

		end_page_writeback(page);

	else

		unlock_page(page);

	blk_queue_exit(bdev->bd_queue);

	return result;

}

EXPORT_SYMBOL_GPL(bdev_write_page);

include/linux/blkdev.h

+2 −0
Original line number Diff line number Diff line
@@ -794,6 +794,8 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t, 
extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,

			 struct scsi_ioctl_command __user *);



extern int blk_queue_enter(struct request_queue *q, gfp_t gfp);

extern void blk_queue_exit(struct request_queue *q);

extern void blk_start_queue(struct request_queue *q);

extern void blk_stop_queue(struct request_queue *q);

extern void blk_sync_queue(struct request_queue *q);

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