rtc: nvmem: fix possible use after free (bba3d2da) · Commits · 戴 / test

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 ("rtc: nvmem: use devm_nvmem_register()") Reported-by:

kernel test robot <lkp@intel.com> Signed-off-by:

Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/nvmem.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -12,6 +12,7 @@
		#include <linux/types.h>
		#include <linux/nvmem-consumer.h>
		#include <linux/rtc.h>
		#include <linux/slab.h>
		#include <linux/sysfs.h>

		/*
		@@ -45,9 +46,7 @@ static int rtc_nvram_register(struct rtc_device *rtc,
		{
		int err;

		rtc->nvram = devm_kzalloc(rtc->dev.parent,
		sizeof(struct bin_attribute),
		GFP_KERNEL);
		rtc->nvram = kzalloc(sizeof(struct bin_attribute), GFP_KERNEL);
		if (!rtc->nvram)
		return -ENOMEM;

		@@ -64,7 +63,7 @@ static int rtc_nvram_register(struct rtc_device *rtc,
		err = sysfs_create_bin_file(&rtc->dev.parent->kobj,
		rtc->nvram);
		if (err) {
		devm_kfree(rtc->dev.parent, rtc->nvram);
		kfree(rtc->nvram);
		rtc->nvram = NULL;
		}

		@@ -74,6 +73,8 @@ static int rtc_nvram_register(struct rtc_device *rtc,
		static void rtc_nvram_unregister(struct rtc_device *rtc)
		{
		sysfs_remove_bin_file(&rtc->dev.parent->kobj, rtc->nvram);
		kfree(rtc->nvram);
		rtc->nvram = NULL;
		}

		/*

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