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

[Stefano Garzarella]

On Thu, Nov 28, 2019 at 06:32:49PM +0800, pannengyuan wrote:
> Hi,
> I think it's a better way, you can implement this new function before
> this patch.

If you want to do it, so you can send everything together, for me there's
no problem, it was just a suggestion.

If you don't have time, I can do it.

Cheers,
Stefano

> 
> 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
> > 
> > 
> > .
> > 
> 

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