Re: [PATCH] RDMA/restrack: Fix potential invalid address access

[Leon Romanovsky <leon@kernel.org>]

On Fri, Mar 01, 2024 at 05:55:15PM +0800, Wenchao Hao wrote:
> struct rdma_restrack_entry's kern_name was set to KBUILD_MODNAME
> in ib_create_cq(), while if the module exited but forgot del this
> rdma_restrack_entry, it would cause a invalid address access in
> rdma_restrack_clean() when print the owner of this rdma_restrack_entry.

How is it possible to exit owner module without cleaning the resources?

Thanks

> 
> Fix this issue by using kstrdup() to set rdma_restrack_entry's
> kern_name.
> 
> Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
> ---
>  drivers/infiniband/core/restrack.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/infiniband/core/restrack.c b/drivers/infiniband/core/restrack.c
> index 01a499a8b88d..6605011c4edc 100644
> --- a/drivers/infiniband/core/restrack.c
> +++ b/drivers/infiniband/core/restrack.c
> @@ -177,7 +177,8 @@ static void rdma_restrack_attach_task(struct rdma_restrack_entry *res,
>  void rdma_restrack_set_name(struct rdma_restrack_entry *res, const char *caller)
>  {
>  	if (caller) {
> -		res->kern_name = caller;
> +		kfree(res->kern_name);
> +		res->kern_name = kstrdup(caller, GFP_KERNEL);
>  		return;
>  	}
>  
> @@ -195,7 +196,7 @@ void rdma_restrack_parent_name(struct rdma_restrack_entry *dst,
>  			       const struct rdma_restrack_entry *parent)
>  {
>  	if (rdma_is_kernel_res(parent))
> -		dst->kern_name = parent->kern_name;
> +		dst->kern_name = kstrdup(parent->kern_name, GFP_KERNEL);
>  	else
>  		rdma_restrack_attach_task(dst, parent->task);
>  }
> @@ -306,6 +307,7 @@ static void restrack_release(struct kref *kref)
>  		put_task_struct(res->task);
>  		res->task = NULL;
>  	}
> +	kfree(res->kern_name);
>  	complete(&res->comp);
>  }
>  
> -- 
> 2.32.0
>