[PATCH V2] block/nbd: fix memory leak in nbd_open()

[pannengyuan]

From: PanNengyuan <address@hidden>

In currently implementation there will be a memory leak when
nbd_client_connect() returns error status. Here is an easy way to
reproduce:

1. run qemu-iotests as follow and check the result with asan:
    ./check -raw 143

Following is the asan output backtrack:
Direct leak of 40 byte(s) in 1 object(s) allocated from:
    #0 0x7f629688a560 in calloc (/usr/lib64/libasan.so.3+0xc7560)
    #1 0x7f6295e7e015 in g_malloc0  (/usr/lib64/libglib-2.0.so.0+0x50015)
    #2 0x56281dab4642 in qobject_input_start_struct  
/mnt/sdb/qemu-4.2.0-rc0/qapi/qobject-input-visitor.c:295
    #3 0x56281dab1a04 in visit_start_struct  
/mnt/sdb/qemu-4.2.0-rc0/qapi/qapi-visit-core.c:49
    #4 0x56281dad1827 in visit_type_SocketAddress  qapi/qapi-visit-sockets.c:386
    #5 0x56281da8062f in nbd_config   /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1716
    #6 0x56281da8062f in nbd_process_options  
/mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1829
    #7 0x56281da8062f in nbd_open  /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1873

Direct leak of 15 byte(s) in 1 object(s) allocated from:
    #0 0x7f629688a3a0 in malloc (/usr/lib64/libasan.so.3+0xc73a0)
    #1 0x7f6295e7dfbd in g_malloc (/usr/lib64/libglib-2.0.so.0+0x4ffbd)
    #2 0x7f6295e96ace in g_strdup (/usr/lib64/libglib-2.0.so.0+0x68ace)
    #3 0x56281da804ac in nbd_process_options 
/mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1834
    #4 0x56281da804ac in nbd_open /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1873

Indirect leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x7f629688a3a0 in malloc (/usr/lib64/libasan.so.3+0xc73a0)
    #1 0x7f6295e7dfbd in g_malloc (/usr/lib64/libglib-2.0.so.0+0x4ffbd)
    #2 0x7f6295e96ace in g_strdup (/usr/lib64/libglib-2.0.so.0+0x68ace)
    #3 0x56281dab41a3 in qobject_input_type_str_keyval  
/mnt/sdb/qemu-4.2.0-rc0/qapi/qobject-input-visitor.c:536
    #4 0x56281dab2ee9 in visit_type_str  
/mnt/sdb/qemu-4.2.0-rc0/qapi/qapi-visit-core.c:297
    #5 0x56281dad0fa1 in visit_type_UnixSocketAddress_members 
qapi/qapi-visit-sockets.c:141
    #6 0x56281dad17b6 in visit_type_SocketAddress_members  
qapi/qapi-visit-sockets.c:366
    #7 0x56281dad186a in visit_type_SocketAddress qapi/qapi-visit-sockets.c:393
    #8 0x56281da8062f in nbd_config /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1716
    #9 0x56281da8062f in nbd_process_options 
/mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1829
    #10 0x56281da8062f in nbd_open /mnt/sdb/qemu-4.2.0-rc0/block/nbd.c:1873

Reported-by: Euler Robot <address@hidden>
Signed-off-by: PanNengyuan <address@hidden>
---
Changes v2 to v1:
- add a new function to do the common cleanups (suggested by Stefano 
Garzarella).
---
 block/nbd.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/block/nbd.c b/block/nbd.c
index 1239761..f8aa2a8 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -94,6 +94,8 @@ typedef struct BDRVNBDState {
 
 static int nbd_client_connect(BlockDriverState *bs, Error **errp);
 
+static void nbd_free_bdrvstate_prop(BDRVNBDState *s);
+
 static void nbd_channel_error(BDRVNBDState *s, int ret)
 {
     if (ret == -EIO) {
@@ -1486,6 +1488,17 @@ static int nbd_client_connect(BlockDriverState *bs, 
Error **errp)
     }
 }
 
+static void nbd_free_bdrvstate_prop(BDRVNBDState *s)
+{
+    object_unref(OBJECT(s->tlscreds));
+    qapi_free_SocketAddress(s->saddr);
+    g_free(s->export);
+    g_free(s->tlscredsid);
+    if (s->x_dirty_bitmap) {
+        g_free(s->x_dirty_bitmap);
+    }
+}
+
 /*
  * Parse nbd_open options
  */
@@ -1855,10 +1868,7 @@ static int nbd_process_options(BlockDriverState *bs, 
QDict *options,
 
  error:
     if (ret < 0) {
-        object_unref(OBJECT(s->tlscreds));
-        qapi_free_SocketAddress(s->saddr);
-        g_free(s->export);
-        g_free(s->tlscredsid);
+        nbd_free_bdrvstate_prop(s);
     }
     qemu_opts_del(opts);
     return ret;
@@ -1881,6 +1891,7 @@ static int nbd_open(BlockDriverState *bs, QDict *options, 
int flags,
 
     ret = nbd_client_connect(bs, errp);
     if (ret < 0) {
+        nbd_free_bdrvstate_prop(s);
         return ret;
     }
     /* successfully connected */
@@ -1937,12 +1948,7 @@ static void nbd_close(BlockDriverState *bs)
     BDRVNBDState *s = bs->opaque;
 
     nbd_client_close(bs);
-
-    object_unref(OBJECT(s->tlscreds));
-    qapi_free_SocketAddress(s->saddr);
-    g_free(s->export);
-    g_free(s->tlscredsid);
-    g_free(s->x_dirty_bitmap);
+    nbd_free_bdrvstate_prop(s);
 }
 
 static int64_t nbd_getlength(BlockDriverState *bs)
-- 
2.7.2.windows.1