sg: prevent integer overflow when converting from sectors to bytes
This prevents integer overflow when converting the request queue's
max_sectors from sectors to bytes. However, this is a preparation for
extending the data type of max_sectors in struct Scsi_Host and
scsi_host_template. So, it is impossible to happen this integer
overflow for now, because SCSI low-level drivers can not specify
max_sectors greater than 0xffff due to the data type limitation.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 53268aa..8f952af 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -806,6 +806,15 @@
return ret;
}
+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 long
sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
{
@@ -945,7 +954,7 @@
if (val < 0)
return -EINVAL;
val = min_t(int, val,
- queue_max_sectors(sdp->device->request_queue) * 512);
+ max_sectors_bytes(sdp->device->request_queue));
if (val != sfp->reserve.bufflen) {
if (sg_res_in_use(sfp) || sfp->mmap_called)
return -EBUSY;
@@ -955,7 +964,7 @@
return 0;
case SG_GET_RESERVED_SIZE:
val = min_t(int, sfp->reserve.bufflen,
- queue_max_sectors(sdp->device->request_queue) * 512);
+ max_sectors_bytes(sdp->device->request_queue));
return put_user(val, ip);
case SG_SET_COMMAND_Q:
result = get_user(val, ip);
@@ -1095,7 +1104,7 @@
return -ENODEV;
return scsi_ioctl(sdp->device, cmd_in, p);
case BLKSECTGET:
- return put_user(queue_max_sectors(sdp->device->request_queue) * 512,
+ return put_user(max_sectors_bytes(sdp->device->request_queue),
ip);
case BLKTRACESETUP:
return blk_trace_setup(sdp->device->request_queue,
@@ -2085,7 +2094,7 @@
sg_big_buff = def_reserved_size;
bufflen = min_t(int, sg_big_buff,
- queue_max_sectors(sdp->device->request_queue) * 512);
+ max_sectors_bytes(sdp->device->request_queue));
sg_build_reserve(sfp, bufflen);
SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: bufflen=%d, k_use_sg=%d\n",
sfp->reserve.bufflen, sfp->reserve.k_use_sg));