linux-kernel - Re: [PATCH] PCI: endpoint: handle probable NULL pointer access

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Message-ID: <20171024200200.GE21840@bhelgaas-glaptop.roam.corp.google.com>
Date:   Tue, 24 Oct 2017 15:02:00 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Pankaj Dubey <pankaj.dubey@...sung.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH] PCI: endpoint: handle probable NULL pointer access

On Thu, Oct 12, 2017 at 09:27:57AM +0530, Pankaj Dubey wrote:
> controller_group allocation in pci_ep_cfs_init function can fail
> so we should have a check while using it in pci_ep_cfs_add_epc_group
> for registering group, else we will hit NULL pointer access.
> 
> This patch adds required check for the same and returns -EPROBE_DEFER,
> so that endpoint controller driver probe can be reattempted later
> in case controller_group is not allocated because pci_ep_cfs_init is
> not yet called.
> 
> Signed-off-by: Pankaj Dubey <pankaj.dubey@...sung.com>

Looking for Kishon's ack here.

> ---
>  drivers/pci/endpoint/pci-ep-cfs.c   | 7 ++++++-
>  drivers/pci/endpoint/pci-epc-core.c | 4 ++++
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
> index 424fdd6..3cac818 100644
> --- a/drivers/pci/endpoint/pci-ep-cfs.c
> +++ b/drivers/pci/endpoint/pci-ep-cfs.c
> @@ -172,7 +172,12 @@ struct config_group *pci_ep_cfs_add_epc_group(const char *name)
>  	group = &epc_group->group;
>  
>  	config_group_init_type_name(group, name, &pci_epc_type);
> -	ret = configfs_register_group(controllers_group, group);
> +
> +	if (controllers_group)
> +		ret = configfs_register_group(controllers_group, group);
> +	else
> +		ret = -EPROBE_DEFER;
> +
>  	if (ret) {
>  		pr_err("failed to register configfs group for %s\n", name);
>  		goto err_register_group;
> diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> index 42c2a11..d327a2a 100644
> --- a/drivers/pci/endpoint/pci-epc-core.c
> +++ b/drivers/pci/endpoint/pci-epc-core.c
> @@ -518,6 +518,10 @@ __pci_epc_create(struct device *dev, const struct pci_epc_ops *ops,
>  		goto put_dev;
>  
>  	epc->group = pci_ep_cfs_add_epc_group(dev_name(dev));
> +	if (IS_ERR(epc->group)) {
> +		ret = -EPROBE_DEFER;
> +		goto put_dev;
> +	}
>  
>  	return epc;
>  
> -- 
> 2.7.4
>