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: Akinobu 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: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index fbd5a67..e0393cd 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -663,6 +663,7 @@
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 @@
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,
- queue_max_sectors(bdev_get_queue(bdev)));
+ 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)));
diff --git a/block/ioctl.c b/block/ioctl.c
index 7d5c3b2..d6cda81 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -278,6 +278,7 @@
struct backing_dev_info *bdi;
loff_t size;
int ret, n;
+ unsigned int max_sectors;
switch(cmd) {
case BLKFLSBUF:
@@ -375,7 +376,9 @@
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: