rbd: fix two memory leaks

When rbd_do_request() is called it allocates and populates an rbd_req structure to hold information about the osd request to be sent. This is done for the benefit of the callback function (in particular, rbd_req_cb()), which uses this in processing when the request completes.

Synchronous requests provide no callback function, in which case rbd_do_request() waits for the request to complete before returning. This case is not handling the needed free of the rbd_req structure like it should, so it is getting leaked.

Note however that the synchronous case has no need for the rbd_req structure at all. So rather than simply freeing this structure for synchronous requests, just don't allocate it to begin with.

Signed-off-by Alex Elder <[email protected]>

---
  drivers/block/rbd.c |   48 ++++++++++++++++++++++++------------------------
  1 file changed, 24 insertions(+), 24 deletions(-)

drivers/block/rbd.c +24 -24

index acdb4a6..78493e7 100644
@@ -1160,20 +1160,11 @@ static int rbd_do_request(struct request *rq,
  					 struct ceph_msg *),
  			  u64 *ver)
  {
+	struct ceph_osd_client *osdc;
  	struct ceph_osd_request *osd_req;
-	int ret;
+	struct rbd_request *rbd_req = NULL;
  	struct timespec mtime = CURRENT_TIME;
-	struct rbd_request *rbd_req;
-	struct ceph_osd_client *osdc;
-
-	rbd_req = kzalloc(sizeof(*rbd_req), GFP_NOIO);
-	if (!rbd_req)
-		return -ENOMEM;
-
-	if (coll) {
-		rbd_req->coll = coll;
-		rbd_req->coll_index = coll_index;
-	}
+	int ret;
 
  	dout("rbd_do_request object_name=%s ofs=%llu len=%llu coll=%p[%d]\n",
  		object_name, (unsigned long long) ofs,

@@ -1181,10 +1172,8 @@ static int rbd_do_request(struct request *rq,
 
  	osdc = &rbd_dev->rbd_client->client->osdc;
  	osd_req = ceph_osdc_alloc_request(osdc, snapc, 1, false, GFP_NOIO);
-	if (!osd_req) {
-		ret = -ENOMEM;
-		goto done_pages;
-	}
+	if (!osd_req)
+		return -ENOMEM;
 
  	osd_req->r_flags = flags;
  	osd_req->r_pages = pages;

@@ -1192,13 +1181,22 @@ static int rbd_do_request(struct request *rq,
  		osd_req->r_bio = bio;
  		bio_get(osd_req->r_bio);
  	}
-	osd_req->r_callback = rbd_cb;
 
-	rbd_req->rq = rq;
-	rbd_req->bio = bio;
-	rbd_req->pages = pages;
-	rbd_req->len = len;
+	if (rbd_cb) {
+		ret = -ENOMEM;
+		rbd_req = kmalloc(sizeof(*rbd_req), GFP_NOIO);
+		if (!rbd_req)
+			goto done_osd_req;
+
+		rbd_req->rq = rq;
+		rbd_req->bio = bio;
+		rbd_req->pages = pages;
+		rbd_req->len = len;
+		rbd_req->coll = coll;
+		rbd_req->coll_index = coll ? coll_index : 0;
+	}
 
+	osd_req->r_callback = rbd_cb;
  	osd_req->r_priv = rbd_req;
 
  	strncpy(osd_req->r_oid, object_name, sizeof(osd_req->r_oid));

@@ -1233,10 +1231,12 @@ static int rbd_do_request(struct request *rq,
  	return ret;
 
  done_err:
-	bio_chain_put(rbd_req->bio);
-	ceph_osdc_put_request(osd_req);
-done_pages:
+	if (bio)
+		bio_chain_put(osd_req->r_bio);
  	kfree(rbd_req);
+done_osd_req:
+	ceph_osdc_put_request(osd_req);
+
  	return ret;
  }
 

When rbd_req_sync_notify_ack() calls rbd_do_request() it supplies rbd_simple_req_cb() as its callback function. Because the callback is supplied, an rbd_req structure gets allocated and populated so it can be used by the callback. However rbd_simple_req_cb() is not freeing (or even using) the rbd_req structure, so it's getting leaked.

Since rbd_simple_req_cb() has no need for the rbd_req structure, just avoid allocating one for this case. Of the three calls to rbd_do_request(), only the one from rbd_do_op() needs the rbd_req structure, and that call can be distinguished from the other two because it supplies a non-null rbd_collection pointer.

So fix this leak by only allocating the rbd_req structure if a non-null "coll" value is provided to rbd_do_request().

Signed-off-by Alex Elder <[email protected]>

---
  drivers/block/rbd.c |    4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

drivers/block/rbd.c +2 -2

index 78493e7..fca0ebf 100644
@@ -1182,7 +1182,7 @@ static int rbd_do_request(struct request *rq,
  		bio_get(osd_req->r_bio);
  	}
 
-	if (rbd_cb) {
+	if (coll) {
  		ret = -ENOMEM;
  		rbd_req = kmalloc(sizeof(*rbd_req), GFP_NOIO);
  		if (!rbd_req)

@@ -1193,7 +1193,7 @@ static int rbd_do_request(struct request *rq,
  		rbd_req->pages = pages;
  		rbd_req->len = len;
  		rbd_req->coll = coll;
-		rbd_req->coll_index = coll ? coll_index : 0;
+		rbd_req->coll_index = coll_index;
  	}
 
  	osd_req->r_callback = rbd_cb;