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.
Reported-by: TOTE Robot <[email protected]>
Signed-off-by: Tuo Li <[email protected]>
---
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
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 <[email protected]>
> Signed-off-by: Tuo Li <[email protected]>
> ---
> 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
>
Leon Romanovsky wrote on Tue, Aug 10, 2021 at 04:55:42PM +0300:
> 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.
Sounds like static analysis because there's a if (rdma) check in
RDMA_CM_EVENT_DISCONNECTED above, so if that needed check then it will
bug right afterwards
I'd tend to agree I don't think it's possible client->trans is null
there (it's filled right after rdma_create_id which defines the handler,
there might be a window where the callback is called before? But as I
understand it shouldn't be called until we resolve address and connect
then later disconnect)
So, I agree with Leon - unless you have a backtrace of a real bug
let's remove the other 'if' if you want to cleanup something for your
robot.
--
Dominique