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

[pannengyuan]

On 2019/11/28 21:36, Stefano Garzarella wrote:
> On Thu, Nov 28, 2019 at 08:09:31PM +0800, address@hidden wrote:
>> 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) {
>        ^ it is not needed, g_free() handles NULL pointers.
>> +        g_free(s->x_dirty_bitmap);
>> +    }
>> +}
>> +
> 
> Please, split this patch in two patches:
> - the first patch where you add this function and use it in
>   nbd_process_options() and nbd_close()
> - the second patch where you fix the leak in nbd_open()
> 
> Thanks,
> Stefano

Thanks, I will change and split it in next version.

> 
>>  /*
>>   * 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
>>
>>
>>
>