Re: [PATCH v2] qemu-nbd: Fix a memleak in nbd_client_thread()

[Alex Chen <alex.chen@huawei.com>]

On 2020/12/8 21:41, Vladimir Sementsov-Ogievskiy wrote:
> 03.12.2020 16:58, Alex Chen wrote:
>> When the qio_channel_socket_connect_sync() fails
>> we should goto 'out_socket' label to free the 'sioc' instead of
>> goto 'out' label.
>> In addition, there's a lot of redundant code in the successful branch
>> and the error branch, optimize it.
>>
>> Reported-by: Euler Robot <euler.robot@huawei.com>
>> Signed-off-by: Alex Chen <alex.chen@huawei.com>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> ---
>>   qemu-nbd.c | 38 +++++++++++++++-----------------------
>>   1 file changed, 15 insertions(+), 23 deletions(-)
>>
>> diff --git a/qemu-nbd.c b/qemu-nbd.c
>> index a7075c5419..9583ee1af6 100644
>> --- a/qemu-nbd.c
>> +++ b/qemu-nbd.c
>> @@ -265,8 +265,8 @@ static void *nbd_client_thread(void *arg)
>>       char *device = arg;
>>       NBDExportInfo info = { .request_sizes = false, .name = g_strdup("") };
>>       QIOChannelSocket *sioc;
>> -    int fd;
>> -    int ret;
>> +    int fd = -1;
>> +    int ret = EXIT_FAILURE;
>>       pthread_t show_parts_thread;
>>       Error *local_error = NULL;
>>   @@ -278,26 +278,24 @@ static void *nbd_client_thread(void *arg)
>>           goto out;
>>       }
>>   -    ret = nbd_receive_negotiate(NULL, QIO_CHANNEL(sioc),
>> -                                NULL, NULL, NULL, &info, &local_error);
>> -    if (ret < 0) {
>> +    if (nbd_receive_negotiate(NULL, QIO_CHANNEL(sioc),
>> +                              NULL, NULL, NULL, &info, &local_error) < 0) {
>>           if (local_error) {
>>               error_report_err(local_error);
>>           }
>> -        goto out_socket;
>> +        goto out;
>>       }
>>         fd = open(device, O_RDWR);
>>       if (fd < 0) {
>>           /* Linux-only, we can use %m in printf.  */
>>           error_report("Failed to open %s: %m", device);
>> -        goto out_socket;
>> +        goto out;
>>       }
>>   -    ret = nbd_init(fd, sioc, &info, &local_error);
>> -    if (ret < 0) {
>> +    if (nbd_init(fd, sioc, &info, &local_error) < 0) {
>>           error_report_err(local_error);
>> -        goto out_fd;
>> +        goto out;
>>       }
>>         /* update partition table */
>> @@ -311,24 +309,18 @@ static void *nbd_client_thread(void *arg)
>>           dup2(STDOUT_FILENO, STDERR_FILENO);
>>       }
>>   -    ret = nbd_client(fd);
>> -    if (ret) {
>> -        goto out_fd;
>> +    if (nbd_client(fd) == 0) {
>> +        ret = EXIT_SUCCESS;
> 
> It's not obvious that nbd_client() returns 0 on success, it calls ioctl(), which may return something positive in theory..
> 
> So, with s/==/>=/, or with just
> 
> if (nbd_client(fd) < 0) {
>   goto out;
> }
> 
> ret = EXIT_SUCCESS;
> 
> 
> (which is good common pattern I think)
> 
> :
> 

Thanks for your review, I will fix it and send patch v3.

Thanks,
Alex