[PATCH v2] vdpa_sim: fix possible memory leak in vdpasim_net_init() and vdpasim_blk_init()

[ruanjinjie]

Inject fault while probing module, if device_register() fails in
vdpasim_net_init() or vdpasim_blk_init(), but the refcount of kobject is
not decreased to 0, the name allocated in dev_set_name() is leaked.
Fix this by calling put_device(), so that name can be freed in
callback function kobject_cleanup().

(vdpa_sim_net)
unreferenced object 0xffff88807eebc370 (size 16):
  comm "modprobe", pid 3848, jiffies 4362982860 (age 18.153s)
  hex dump (first 16 bytes):
    76 64 70 61 73 69 6d 5f 6e 65 74 00 6b 6b 6b a5  vdpasim_net.kkk.
  backtrace:
    [<ffffffff8174f19e>] __kmalloc_node_track_caller+0x4e/0x150
    [<ffffffff81731d53>] kstrdup+0x33/0x60
    [<ffffffff83a5d421>] kobject_set_name_vargs+0x41/0x110
    [<ffffffff82d87aab>] dev_set_name+0xab/0xe0
    [<ffffffff82d91a23>] device_add+0xe3/0x1a80
    [<ffffffffa0270013>] 0xffffffffa0270013
    [<ffffffff81001c27>] do_one_initcall+0x87/0x2e0
    [<ffffffff813739cb>] do_init_module+0x1ab/0x640
    [<ffffffff81379d20>] load_module+0x5d00/0x77f0
    [<ffffffff8137bc40>] __do_sys_finit_module+0x110/0x1b0
    [<ffffffff83c4d505>] do_syscall_64+0x35/0x80
    [<ffffffff83e0006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

(vdpa_sim_blk)
unreferenced object 0xffff8881070c1250 (size 16):
  comm "modprobe", pid 6844, jiffies 4364069319 (age 17.572s)
  hex dump (first 16 bytes):
    76 64 70 61 73 69 6d 5f 62 6c 6b 00 6b 6b 6b a5  vdpasim_blk.kkk.
  backtrace:
    [<ffffffff8174f19e>] __kmalloc_node_track_caller+0x4e/0x150
    [<ffffffff81731d53>] kstrdup+0x33/0x60
    [<ffffffff83a5d421>] kobject_set_name_vargs+0x41/0x110
    [<ffffffff82d87aab>] dev_set_name+0xab/0xe0
    [<ffffffff82d91a23>] device_add+0xe3/0x1a80
    [<ffffffffa0220013>] 0xffffffffa0220013
    [<ffffffff81001c27>] do_one_initcall+0x87/0x2e0
    [<ffffffff813739cb>] do_init_module+0x1ab/0x640
    [<ffffffff81379d20>] load_module+0x5d00/0x77f0
    [<ffffffff8137bc40>] __do_sys_finit_module+0x110/0x1b0
    [<ffffffff83c4d505>] do_syscall_64+0x35/0x80
    [<ffffffff83e0006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

Signed-off-by: ruanjinjie <ruanjinjie@xxxxxxxxxx>
---
v2:
- add fault inject message
---
 drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 4 +++-
 drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
index c6db1a1baf76..f745926237a8 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
@@ -427,8 +427,10 @@ static int __init vdpasim_blk_init(void)
 	int ret;
 
 	ret = device_register(&vdpasim_blk_mgmtdev);
-	if (ret)
+	if (ret) {
+		put_device(&vdpasim_blk_mgmtdev);
 		return ret;
+	}
 
 	ret = vdpa_mgmtdev_register(&mgmt_dev);
 	if (ret)
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
index c3cb225ea469..11f5a121df24 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
@@ -305,8 +305,10 @@ static int __init vdpasim_net_init(void)
 	int ret;
 
 	ret = device_register(&vdpasim_net_mgmtdev);
-	if (ret)
+	if (ret) {
+		put_device(&vdpasim_net_mgmtdev);
 		return ret;
+	}
 
 	ret = vdpa_mgmtdev_register(&mgmt_dev);
 	if (ret)
-- 
2.25.1