[PATCH] block: fix BLKSECTGET ioctl when max_sectors is greater than USHRT_MAX

[PATCH] block: fix BLKSECTGET ioctl when max_sectors is greater than USHRT_MAX

[Akinobu Mita]

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>
---
 block/compat_ioctl.c | 6 ++++--
 block/ioctl.c        | 5 ++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

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 @@ 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,
-					 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 @@ 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:
-- 
1.8.3.2

[PATCH] block: fix SG_[GS]ET_RESERVED_SIZE ioctl when max_sectors is huge

[Akinobu Mita]

SG_GET_RESERVED_SIZE and SG_SET_RESERVED_SIZE ioctls access a reserved
buffer in bytes as int type.  The value needs to be capped at the request
queue's max_sectors.  But integer overflow is not correctly handled in
the calculation when converting max_sectors from sectors to bytes.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
---
 block/scsi_ioctl.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 2648797..6174bba 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -82,9 +82,18 @@ static int sg_set_timeout(struct request_queue *q, int __user *p)
 	return err;
 }
 
+static int max_sectors_bytes(struct request_queue *q)
+{
+	unsigned int max_sectors = queue_max_sectors(q);
+
+	max_sectors = min_t(unsigned int, max_sectors, INT_MAX >> 9);
+
+	return max_sectors << 9;
+}
+
 static int sg_get_reserved_size(struct request_queue *q, int __user *p)
 {
-	unsigned val = min(q->sg_reserved_size, queue_max_sectors(q) << 9);
+	int val = min_t(int, q->sg_reserved_size, max_sectors_bytes(q));
 
 	return put_user(val, p);
 }
@@ -98,10 +107,8 @@ static int sg_set_reserved_size(struct request_queue *q, int __user *p)
 
 	if (size < 0)
 		return -EINVAL;
-	if (size > (queue_max_sectors(q) << 9))
-		size = queue_max_sectors(q) << 9;
 
-	q->sg_reserved_size = size;
+	q->sg_reserved_size = min(size, max_sectors_bytes(q));
 	return 0;
 }
 
-- 
1.8.3.2