Re: [PATCH v2] rpc: fix memory leak in virNetServerClientNew and virNetServerProgramDispatchCall
On 09/29/2022 21:31, Michal Prívozník wrote:
On 9/27/22 17:38, Jiang Jiacheng wrote:
> From: jiangjiacheng <jiangjiacheng(a)huawei.com>
>
> In virNetServerProgramDispatchCall, The arg is passed as a void* and used to point
> to a certain struct depended on the dispatcher, so I think it's the memory of
the
> struct's member that leaks and this memory shuld be freed by xdr_free.
>
> In virNetServerClientNew, client->rx is assigned by invoking
virNetServerClientNew,
> but isn't freed if client->privateData's initialization failed, which
leads to a
> memory leak. Thanks to Liang Peng's suggestion, put
virNetMessageFree(client->rx)
> into virNetServerClientDispose() to release the memory.
>
> Signed-off-by: jiangjiacheng <jiangjiacheng(a)huawei.com>
> ---
> src/rpc/virnetserverclient.c | 2 ++
> src/rpc/virnetserverprogram.c | 12 +++++++++---
> 2 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/src/rpc/virnetserverclient.c b/src/rpc/virnetserverclient.c
> index a7d2dfa795..30f6af7be5 100644
> --- a/src/rpc/virnetserverclient.c
> +++ b/src/rpc/virnetserverclient.c
> @@ -931,6 +931,8 @@ void virNetServerClientDispose(void *obj)
> PROBE(RPC_SERVER_CLIENT_DISPOSE,
> "client=%p", client);
>
> + if (client->rx)
> + virNetMessageFree(client->rx);
> if (client->privateData)
> client->privateDataFreeFunc(client->privateData);
Yeah, this one is a genuine memleak. IIUC it can be reproduced by:
client = virNetServerClientNew(...);
virObjectUnref(client);
>
> diff --git a/src/rpc/virnetserverprogram.c b/src/rpc/virnetserverprogram.c
> index 3ddf9f0428..a813e821a3 100644
> --- a/src/rpc/virnetserverprogram.c
> +++ b/src/rpc/virnetserverprogram.c
> @@ -409,11 +409,15 @@ virNetServerProgramDispatchCall(virNetServerProgram *prog,
> if (virNetMessageDecodePayload(msg, dispatcher->arg_filter, arg) < 0)
> goto error;
>
> - if (!(identity = virNetServerClientGetIdentity(client)))
> + if (!(identity = virNetServerClientGetIdentity(client))) {
> + xdr_free(dispatcher->arg_filter, arg);
But here I believe we also need to free dispatcher->ret_filter:
xdr_free(dispatcher->ret_filter, ret);
Hi Michal,
I'm not sure why we need to free ret here. IIRC, xdr_free is to free
memory pointed by *ret instead of ret. For example, if ret is pointing
to a struct which contains a string, like:
struct Test {
char *str;
}
then I think xdr_free(dispatcher->ret_filter, ret) will free str instead
of struct Test itself. So I think we will only need to call
xdr_free(dispatcher->ret_filter, ret) after we call
(dispatcher->func)(server, client, msg, &rerr, arg, ret).
Thanks,
Peng
and in the rest of the hunks too. But at this point, I wonder whether we
shouldn't have just two places where this free is done: one in
successful path and one under error label.
Michal