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

[pannengyuan]

Hi,
I think it's a better way, you can implement this new function before
this patch.

Thanks.

On 2019/11/28 17:01, Stefano Garzarella wrote:
> On Thu, Nov 28, 2019 at 04:40:10PM +0800, address@hidden wrote:
> 
> Hi,
> I don't know nbd code very well, the patch LGTM, but just a comment
> below:
> 
>> 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>
>> ---
>>  block/nbd.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/block/nbd.c b/block/nbd.c
>> index 1239761..bc40a25 100644
>> --- a/block/nbd.c
>> +++ b/block/nbd.c
>> @@ -1881,6 +1881,11 @@ static int nbd_open(BlockDriverState *bs, QDict 
>> *options, int flags,
>>  
>>      ret = nbd_client_connect(bs, errp);
>>      if (ret < 0) {
>> +        object_unref(OBJECT(s->tlscreds));
>> +        qapi_free_SocketAddress(s->saddr);
>> +        g_free(s->export);
>> +        g_free(s->tlscredsid);
>> +        g_free(s->x_dirty_bitmap);
> 
> Since with this patch we are doing these cleanups in 3 places (here,
> nbd_close(), and nbd_process_options()), should be better to add a new
> function to do these cleanups?
> 
> Maybe I'd create a series adding a patch before this one, implementing this
> new function, and change this patch calling it.
> 
> Thanks,
> Stefano
> 
> 
> .
>