Re: [PATCH v4 05/11] firewall: introduce stm32_firewall framework
From: Simon Horman <horms@kernel.org>
Date: 2023-08-12 14:09:32
Also in:
alsa-devel, dmaengine, linux-arm-kernel, linux-crypto, linux-devicetree, linux-i2c, linux-iio, linux-media, linux-mmc, linux-phy, linux-serial, linux-spi, linux-usb, lkml
On Fri, Aug 11, 2023 at 12:07:25PM +0200, Gatien Chevallier wrote: ...
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diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c new file mode 100644 index 000000000000..900f3b052a66 --- /dev/null +++ b/drivers/bus/stm32_firewall.c@@ -0,0 +1,293 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2023, STMicroelectronics - All Rights Reserved + */ + +#include <linux/bitfield.h> +#include <linux/bits.h> +#include <linux/bus/stm32_firewall_device.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_platform.h> +#include <linux/platform_device.h> +#include <linux/types.h> +#include <linux/slab.h> + +#include "stm32_firewall.h" + +/* Corresponds to STM32_FIREWALL_MAX_EXTRA_ARGS + firewall ID */ +#define STM32_FIREWALL_MAX_ARGS (STM32_FIREWALL_MAX_EXTRA_ARGS + 1) + +static LIST_HEAD(firewall_controller_list); +static DEFINE_MUTEX(firewall_controller_list_lock); + +/* Firewall device API */ +int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall, + unsigned int nb_firewall) +{ + struct stm32_firewall_controller *ctrl; + struct of_phandle_iterator it; + unsigned int i, j = 0; + int err; + + if (!firewall || !nb_firewall) + return -EINVAL; + + /* Parse property with phandle parsed out */ + of_for_each_phandle(&it, err, np, "feature-domains", "#feature-domain-cells", 0) { + struct of_phandle_args provider_args; + struct device_node *provider = it.node; + const char *fw_entry; + bool match = false; + + if (err) { + pr_err("Unable to get feature-domains property for node %s\n, err: %d", + np->full_name, err); + of_node_put(provider); + return err; + } + + if (j > nb_firewall) { + pr_err("Too many firewall controllers"); + of_node_put(provider); + return -EINVAL; + } + + provider_args.args_count = of_phandle_iterator_args(&it, provider_args.args, + STM32_FIREWALL_MAX_ARGS); + + /* Check if the parsed phandle corresponds to a registered firewall controller */ + mutex_lock(&firewall_controller_list_lock); + list_for_each_entry(ctrl, &firewall_controller_list, entry) { + if (ctrl->dev->of_node->phandle == it.phandle) { + match = true; + firewall[j].firewall_ctrl = ctrl; + break; + } + } + mutex_unlock(&firewall_controller_list_lock); + + if (!match) { + firewall[j].firewall_ctrl = NULL; + pr_err("No firewall controller registered for %s\n", np->full_name); + of_node_put(provider); + return -ENODEV; + } + + err = of_property_read_string_index(np, "feature-domain-names", j, &fw_entry); + if (err == 0) + firewall[j].entry = fw_entry; + + /* Handle the case when there are no arguments given along with the phandle */ + if (provider_args.args_count < 0 || + provider_args.args_count > STM32_FIREWALL_MAX_ARGS) { + of_node_put(provider); + return -EINVAL; + } else if (provider_args.args_count == 0) { + firewall[j].extra_args_size = 0; + firewall[j].firewall_id = U32_MAX; + j++; + continue; + } + + /* The firewall ID is always the first argument */ + firewall[j].firewall_id = provider_args.args[0]; + + /* Extra args start at the third argument */ + for (i = 0; i < provider_args.args_count; i++) + firewall[j].extra_args[i] = provider_args.args[i + 1];
Hi Gatien, Above it is checked that the maximum value of provider_args.args_count is STM32_FIREWALL_MAX_ARGS. So here the maximum value of i is STM32_FIREWALL_MAX_ARGS - 1. STM32_FIREWALL_MAX_ARGS is defined as STM32_FIREWALL_MAX_EXTRA_ARGS + 1 And STM32_FIREWALL_MAX_EXTRA_ARGS is defined as 5. So the maximum value of i is (5 + 1 - 1) = 5. firewall[j] is of type struct stm32_firewall. And its args field has STM32_FIREWALL_MAX_EXTRA_ARGS (5) elements. Thus the maximum valid index is (5 - 1) = 4. But the line above may access index 5. Flagged by Smatch.
+ + /* Remove the firewall ID arg that is not an extra argument */ + firewall[j].extra_args_size = provider_args.args_count - 1; + + j++; + } + + return 0; +} +EXPORT_SYMBOL_GPL(stm32_firewall_get_firewall);
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diff --git a/include/linux/bus/stm32_firewall_device.h b/include/linux/bus/stm32_firewall_device.h new file mode 100644 index 000000000000..7b4450a8ec15 --- /dev/null +++ b/include/linux/bus/stm32_firewall_device.h@@ -0,0 +1,141 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2023, STMicroelectronics - All Rights Reserved + */ + +#ifndef STM32_FIREWALL_DEVICE_H +#define STM32_FIREWALL_DEVICE_H + +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/types.h> + +#define STM32_FIREWALL_MAX_EXTRA_ARGS 5 + +/* Opaque reference to stm32_firewall_controller */ +struct stm32_firewall_controller; + +/** + * struct stm32_firewall - Information on a device's firewall. Each device can have more than one + * firewall. + * + * @firewall_ctrl: Pointer referencing a firewall controller of the device. It is + * opaque so a device cannot manipulate the controller's ops or access + * the controller's data + * @extra_args: Extra arguments that are implementation dependent + * @entry: Name of the firewall entry + * @extra_args_size: Number of extra arguments + * @firewall_id: Firewall ID associated the device for this firewall controller + */ +struct stm32_firewall { + struct stm32_firewall_controller *firewall_ctrl; + u32 extra_args[STM32_FIREWALL_MAX_EXTRA_ARGS]; + const char *entry; + size_t extra_args_size; + u32 firewall_id; +};
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