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bba3d2daa8
In cas of probe failure, devres may free the memory allocated for
rtc->nvram before devm_rtc_release_device() is called. This leads to
rtc_nvram_unregister using it after being freed which may lead to a crash.
This has been shown to happen after commit 461e557b97 ("rtc: nvmem: use
devm_nvmem_register()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
111 lines
2.5 KiB
C
111 lines
2.5 KiB
C
/*
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* RTC subsystem, nvmem interface
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*
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* Copyright (C) 2017 Alexandre Belloni
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/err.h>
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#include <linux/types.h>
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#include <linux/nvmem-consumer.h>
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#include <linux/rtc.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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/*
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* Deprecated ABI compatibility, this should be removed at some point
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*/
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static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
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static ssize_t
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rtc_nvram_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr,
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char *buf, loff_t off, size_t count)
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{
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dev_warn_once(kobj_to_dev(kobj), nvram_warning);
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return nvmem_device_read(attr->private, off, count, buf);
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}
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static ssize_t
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rtc_nvram_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr,
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char *buf, loff_t off, size_t count)
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{
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dev_warn_once(kobj_to_dev(kobj), nvram_warning);
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return nvmem_device_write(attr->private, off, count, buf);
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}
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static int rtc_nvram_register(struct rtc_device *rtc,
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struct nvmem_device *nvmem, size_t size)
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{
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int err;
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rtc->nvram = kzalloc(sizeof(struct bin_attribute), GFP_KERNEL);
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if (!rtc->nvram)
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return -ENOMEM;
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rtc->nvram->attr.name = "nvram";
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rtc->nvram->attr.mode = 0644;
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rtc->nvram->private = nvmem;
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sysfs_bin_attr_init(rtc->nvram);
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rtc->nvram->read = rtc_nvram_read;
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rtc->nvram->write = rtc_nvram_write;
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rtc->nvram->size = size;
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err = sysfs_create_bin_file(&rtc->dev.parent->kobj,
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rtc->nvram);
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if (err) {
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kfree(rtc->nvram);
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rtc->nvram = NULL;
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}
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return err;
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}
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static void rtc_nvram_unregister(struct rtc_device *rtc)
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{
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sysfs_remove_bin_file(&rtc->dev.parent->kobj, rtc->nvram);
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kfree(rtc->nvram);
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rtc->nvram = NULL;
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}
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/*
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* New ABI, uses nvmem
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*/
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int rtc_nvmem_register(struct rtc_device *rtc,
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struct nvmem_config *nvmem_config)
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{
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struct nvmem_device *nvmem;
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if (!nvmem_config)
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return -ENODEV;
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nvmem_config->dev = rtc->dev.parent;
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nvmem_config->owner = rtc->owner;
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nvmem = devm_nvmem_register(rtc->dev.parent, nvmem_config);
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if (IS_ERR(nvmem))
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return PTR_ERR(nvmem);
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/* Register the old ABI */
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if (rtc->nvram_old_abi)
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rtc_nvram_register(rtc, nvmem, nvmem_config->size);
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return 0;
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}
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EXPORT_SYMBOL_GPL(rtc_nvmem_register);
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void rtc_nvmem_unregister(struct rtc_device *rtc)
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{
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/* unregister the old ABI */
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if (rtc->nvram)
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rtc_nvram_unregister(rtc);
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}
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