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Commit 63f26496 authored by Akinobu Mita's avatar Akinobu Mita Committed by Jens Axboe
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block: fix BLKSECTGET ioctl when max_sectors is greater than USHRT_MAX 



BLKSECTGET ioctl loads the request queue's max_sectors as unsigned
short value to the argument pointer.  So if the max_sector is greater
than USHRT_MAX, the upper 16 bits of that is just discarded.

In such case, USHRT_MAX is more preferable than the lower 16 bits of
max_sectors.

Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: linux-scsi@vger.kernel.org
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 16e15565

block/compat_ioctl.c

+4 −2
Original line number Diff line number Diff line
@@ -663,6 +663,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg) 
	fmode_t mode = file->f_mode;

	struct backing_dev_info *bdi;

	loff_t size;

	unsigned int max_sectors;



	/*

	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
@@ -718,8 +719,9 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg) 
	case BLKSSZGET: /* get block device hardware sector size */

		return compat_put_int(arg, bdev_logical_block_size(bdev));

	case BLKSECTGET:

		return compat_put_ushort(arg,

		max_sectors = min_t(unsigned int, USHRT_MAX,

				    queue_max_sectors(bdev_get_queue(bdev)));

		return compat_put_ushort(arg, max_sectors);

	case BLKROTATIONAL:

		return compat_put_ushort(arg,

					 !blk_queue_nonrot(bdev_get_queue(bdev)));

block/ioctl.c

+4 −1
Original line number Diff line number Diff line
@@ -278,6 +278,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, 
	struct backing_dev_info *bdi;

	loff_t size;

	int ret, n;

	unsigned int max_sectors;



	switch(cmd) {

	case BLKFLSBUF:
@@ -375,7 +376,9 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, 
	case BLKDISCARDZEROES:

		return put_uint(arg, bdev_discard_zeroes_data(bdev));

	case BLKSECTGET:

		return put_ushort(arg, queue_max_sectors(bdev_get_queue(bdev)));

		max_sectors = min_t(unsigned int, USHRT_MAX,

				    queue_max_sectors(bdev_get_queue(bdev)));

		return put_ushort(arg, max_sectors);

	case BLKROTATIONAL:

		return put_ushort(arg, !blk_queue_nonrot(bdev_get_queue(bdev)));

	case BLKRASET: