Re: [PATCH] net: 9p: Fix possible null-pointer dereference in p9_cm_event_handler()
From: Leon Romanovsky
Date: Tue Aug 10 2021 - 09:55:51 EST
On Tue, Aug 10, 2021 at 06:20:07AM -0700, Tuo Li wrote:
> The variable rdma is checked when event->event is equal to
> RDMA_CM_EVENT_DISCONNECTED:
> if (rdma)
>
> This indicates that it can be NULL. If so, a null-pointer dereference will
> occur when calling complete():
> complete(&rdma->cm_done);
>
> To fix this possible null-pointer dereference, calling complete() only
> when rdma is not NULL.
You need to explain how is it possible and blindly set if () checks.
I would say first "if (rdma)" is not needed, but don't know for sure.
>
> Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>
> Signed-off-by: Tuo Li <islituo@xxxxxxxxx>
> ---
> net/9p/trans_rdma.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/9p/trans_rdma.c b/net/9p/trans_rdma.c
> index af0a8a6cd3fd..fb3435dfd071 100644
> --- a/net/9p/trans_rdma.c
> +++ b/net/9p/trans_rdma.c
> @@ -285,7 +285,8 @@ p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
> default:
> BUG();
> }
> - complete(&rdma->cm_done);
> + if (rdma)
> + complete(&rdma->cm_done);
> return 0;
> }
>
> --
> 2.25.1
>