ore: Fix out-of-bounds access in _ios_obj()

commit 9e62bb44 upstream.

_ios_obj() is accessed by group_index not device_table index.

The oc->comps array is only a group_full of devices at a time
it is not like ore_comp_dev() which is indexed by a global
device_table index.

This did not BUG until now because exofs only uses a single
COMP for all devices. But with other FSs like PanFS this is
not true.

This bug was only in the write_path, all other users were
using it correctly

[This is a bug since 3.2 Kernel]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/exofs/ore.c

@@ -837,11 +837,11 @@ static int _write_mirror(struct ore_io_state *ios, int cur_comp)
 				bio->bi_rw |= REQ_WRITE;
 			}
 
-			osd_req_write(or, _ios_obj(ios, dev), per_dev->offset,
-				      bio, per_dev->length);
+			osd_req_write(or, _ios_obj(ios, cur_comp),
+				      per_dev->offset, bio, per_dev->length);
 			ORE_DBGMSG("write(0x%llx) offset=0x%llx "
 				      "length=0x%llx dev=%d\n",
-				     _LLU(_ios_obj(ios, dev)->id),
+				     _LLU(_ios_obj(ios, cur_comp)->id),
 				     _LLU(per_dev->offset),
 				     _LLU(per_dev->length), dev);
 		} else if (ios->kern_buff) {
@@ -853,20 +853,20 @@ static int _write_mirror(struct ore_io_state *ios, int cur_comp)
 			       (ios->si.unit_off + ios->length >
 				ios->layout->stripe_unit));
 
-			ret = osd_req_write_kern(or, _ios_obj(ios, per_dev->dev),
+			ret = osd_req_write_kern(or, _ios_obj(ios, cur_comp),
 						 per_dev->offset,
 						 ios->kern_buff, ios->length);
 			if (unlikely(ret))
 				goto out;
 			ORE_DBGMSG2("write_kern(0x%llx) offset=0x%llx "
 				      "length=0x%llx dev=%d\n",
-				     _LLU(_ios_obj(ios, dev)->id),
+				     _LLU(_ios_obj(ios, cur_comp)->id),
 				     _LLU(per_dev->offset),
 				     _LLU(ios->length), per_dev->dev);
 		} else {
-			osd_req_set_attributes(or, _ios_obj(ios, dev));
+			osd_req_set_attributes(or, _ios_obj(ios, cur_comp));
 			ORE_DBGMSG2("obj(0x%llx) set_attributes=%d dev=%d\n",
-				     _LLU(_ios_obj(ios, dev)->id),
+				     _LLU(_ios_obj(ios, cur_comp)->id),
 				     ios->out_attr_len, dev);
 		}