RE: Potential NULL pointer dereference in drivers/infiniband/core

["Steve Wise" <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>]

> 
> Steve,
> 
> Can you look at the iWarp code flow described below?

sure:

> 
> > My name is Shaobo He and I am a graduate student at University of Utah.
> > I am applying a static analysis tool to the Linux device drivers and
> > got an error trace of null pointer dereference in
> > drivers/infiniband/core starting from function `ucma_accept`: it calls
> > `rdma_accept` with the second argument being NULL. In `rdma_accept`,
> > `cma_accept_iw` is called with the second argument also being NULL.
> > Then in `cma_accept_iw`, `cma_modify_qp_rtr` can return 0 if `id_priv-
> > >id.qp` is NULL, which can be suggested by an if statement in
> > `rdma_accept`. Finally, the second argument `conn_param` of
> > `cma_accept_iw` gets dereferenced. As you can see, the error trace is
> > only plausible since it depends on certain conditions. Therefore, I was
> > wondering if you could confirm it.
> 
> Based on a quick look, this looks like it's at least a problem in how
conn_param is
> verified.  IB allows conn_param to be optional, whereas iWarp requires it.
Since
> this is coming from user space, we can crash.
> 

Agreed.  cma_accept_iw() needs to either fail the accept for a NULL conn_param,
or generate values for the iw_param struct if conn_param is NULL.  I suggest the
former.  Something like:


diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 3e70a9c..c377afc 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -3583,6 +3583,9 @@ static int cma_accept_iw(struct rdma_id_private *id_priv,
        struct iw_cm_conn_param iw_param;
        int ret;

+       if (!conn_param)
+               return -EINVAL;
+
        ret = cma_modify_qp_rtr(id_priv, conn_param);
        if (ret)
                return ret;


---
Steve.

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