From: Dongsheng Yang <dongsheng.yang@easystack.cn>
Date: Fri, 9 Aug 2019 07:05:27 +0000
Subject: rbd: fix response length parameter for encoded strings
Git-commit: 5435d2069503e2aa89c34a94154f4f2fa4a0c9c4
Patch-mainline: v5.4-rc1
References: jsc#SES-1134

rbd_dev_image_id() allocates space for length but passes a smaller
value to rbd_obj_method_sync().  rbd_dev_v2_object_prefix() doesn't
allocate space for length.  Fix both to be consistent.

Signed-off-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 drivers/block/rbd.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index c8fb886aebd4..69db7385c8df 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -5669,17 +5669,20 @@ static int rbd_dev_v2_image_size(struct rbd_device *rbd_dev)
 
 static int rbd_dev_v2_object_prefix(struct rbd_device *rbd_dev)
 {
+	size_t size;
 	void *reply_buf;
 	int ret;
 	void *p;
 
-	reply_buf = kzalloc(RBD_OBJ_PREFIX_LEN_MAX, GFP_KERNEL);
+	/* Response will be an encoded string, which includes a length */
+	size = sizeof(__le32) + RBD_OBJ_PREFIX_LEN_MAX;
+	reply_buf = kzalloc(size, GFP_KERNEL);
 	if (!reply_buf)
 		return -ENOMEM;
 
 	ret = rbd_obj_method_sync(rbd_dev, &rbd_dev->header_oid,
 				  &rbd_dev->header_oloc, "get_object_prefix",
-				  NULL, 0, reply_buf, RBD_OBJ_PREFIX_LEN_MAX);
+				  NULL, 0, reply_buf, size);
 	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
 	if (ret < 0)
 		goto out;
@@ -6696,7 +6699,6 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
 	dout("rbd id object name is %s\n", oid.name);
 
 	/* Response will be an encoded string, which includes a length */
-
 	size = sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX;
 	response = kzalloc(size, GFP_NOIO);
 	if (!response) {
@@ -6708,7 +6710,7 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
 
 	ret = rbd_obj_method_sync(rbd_dev, &oid, &rbd_dev->header_oloc,
 				  "get_id", NULL, 0,
-				  response, RBD_IMAGE_ID_LEN_MAX);
+				  response, size);
 	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
 	if (ret == -ENOENT) {
 		image_id = kstrdup("", GFP_KERNEL);