[PATCH v4] block: add check that partition length needs to be aligned with block size

[Min Li]

Before calling add partition or resize partition, there is no check
on whether the length is aligned with the logical block size.
If the logical block size of the disk is larger than 512 bytes,
then the partition size maybe not the multiple of the logical block size,
and when the last sector is read, bio_truncate() will adjust the bio size,
resulting in an IO error if the size of the read command is smaller than
the logical block size.If integrity data is supported, this will also
result in a null pointer dereference when calling bio_integrity_free.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Min Li <min15.li@xxxxxxxxxxx>

---
Changes from v1:

- Add a space after /* and before */.
- Move length alignment check before the "start = p.start >> SECTOR_SHIFT"
- Move check for p.start being aligned together with this length alignment check.

Changes from v2:

- Add the assignment on the first line and merge the two lines into one.

Changes from v3:

- Change the blksz to unsigned int.
- Add check if p.start and p.length are negative.
---
 block/ioctl.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/block/ioctl.c b/block/ioctl.c
index 3be11941fb2d..a8061c2fcae0 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -16,9 +16,10 @@
 static int blkpg_do_ioctl(struct block_device *bdev,
 			  struct blkpg_partition __user *upart, int op)
 {
+	unsigned int blksz = bdev_logical_block_size(bdev);
 	struct gendisk *disk = bdev->bd_disk;
 	struct blkpg_partition p;
-	long long start, length;
+	sector_t start, length;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
@@ -33,14 +34,17 @@ static int blkpg_do_ioctl(struct block_device *bdev,
 	if (op == BLKPG_DEL_PARTITION)
 		return bdev_del_partition(disk, p.pno);
 
+	if (p.start < 0 || p.length <= 0 || p.start + p.length < 0)
+		return -EINVAL;
+	/* Check that the partition is aligned to the block size */
+	if (!IS_ALIGNED(p.start | p.length, blksz))
+		return -EINVAL;
+
 	start = p.start >> SECTOR_SHIFT;
 	length = p.length >> SECTOR_SHIFT;
 
 	switch (op) {
 	case BLKPG_ADD_PARTITION:
-		/* check if partition is aligned to blocksize */
-		if (p.start & (bdev_logical_block_size(bdev) - 1))
-			return -EINVAL;
 		return bdev_add_partition(disk, p.pno, start, length);
 	case BLKPG_RESIZE_PARTITION:
 		return bdev_resize_partition(disk, p.pno, start, length);
-- 
2.34.1