Re: [PATCH AUTOSEL 5.3 15/71] rbd: fix response length parameter for encoded strings

Sasha Levin <sashal@xxxxxxxxxx> · Tue, 8 Oct 2019 17:29:44 -0400

On Tue, Oct 01, 2019 at 07:15:49PM +0200, Ilya Dryomov wrote:
On Tue, Oct 1, 2019 at 6:39 PM Sasha Levin <sashal@xxxxxxxxxx> wrote:

From: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>

[ Upstream commit 5435d2069503e2aa89c34a94154f4f2fa4a0c9c4 ]

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@xxxxxxxxxxxx>
Reviewed-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 c8fb886aebd4e..69db7385c8df5 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);

Hi Sasha,

This patch just made things consistent, there was no bug here.  I don't
think it should be backported.

I'll drop it, thanks!

--
Thanks,
Sasha






