path: root/block
diff options
authorStefan Haberland <sth@linux.vnet.ibm.com>2016-12-19 17:15:50 +0100
committerJens Axboe <axboe@fb.com>2016-12-19 09:20:59 -0700
commit633395b67bb222f85bb8f825c7751a54b9ec84ee (patch)
tree871ee04fe6944d654043760bc36e02c453620e63 /block
parentc965809c669da004b660e5923b8add8fac5a7dc8 (diff)
block: check partition alignment
Partitions that are not aligned to the blocksize of a device may cause invalid I/O requests because the blocklayer cares only about alignment within the partition when building requests on partitions. device |--------4096--------|--------4096--------|--------4096--------| partition offset 512byte |-512-|--------4096--------|--------4096--------|--------4096--------| When reading/writing one 4k block of the partition this maps to reading/writing with an offset of 512 byte of the device leading to unaligned requests for the device which in turn may cause unexpected behavior of the device driver. For DASD devices we have to translate the block number into a cylinder, head, record format. The unaligned requests lead to wrong calculation and therefore to misdirected I/O. In a "good" case this leads to I/O errors because the underlying hardware detects the wrong addressing. In a worst case scenario this might destroy data on the device. To prevent partitions that are not aligned to the physical blocksize of a device check for the alignment in the blkpg_ioctl. Signed-off-by: Stefan Haberland <sth@linux.vnet.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
1 files changed, 3 insertions, 0 deletions
diff --git a/block/ioctl.c b/block/ioctl.c
index f856963204f4..656c8c6ed206 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -45,6 +45,9 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
|| pstart < 0 || plength < 0 || partno > 65535)
return -EINVAL;
+ /* check if partition is aligned to blocksize */
+ if (p.start & (bdev_logical_block_size(bdev) - 1))
+ return -EINVAL;