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From:   Yang Yingliang <yangyingliang@huawei.com>
To:     <linux-kernel@vger.kernel.org>
CC:     <lvjianmin@loongson.cn>, <chenhuacai@kernel.org>,
        <chenhuacai@loongson.cn>
Subject: [PATCH] platform/loongarch: laptop: fix possible UAF and simplify return in generic_acpi_laptop_init()
Date:   Fri, 14 Oct 2022 09:52:12 +0800
Message-ID: <20221014015212.1150629-1-yangyingliang@huawei.com>
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Current the return value of 'sub_driver->init' is not checked,
if sparse_keymap_setup() called in the init function fails,
'generic_inputdev' is freed, then it willl lead a UAF when
using it in generic_acpi_laptop_init(). Fix it by checking
return value. Set generic_inputdev to NULL after free to avoid
double free it.

The error code in generic_subdriver_init() is always negative,
the return of generic_subdriver_init() can be simplified.

Fixes: 6246ed09111f ("LoongArch: Add ACPI-based generic laptop driver")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 drivers/platform/loongarch/loongson-laptop.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/loongarch/loongson-laptop.c b/drivers/platform/loongarch/loongson-laptop.c
index f0166ad5d2c2..572290abf151 100644
--- a/drivers/platform/loongarch/loongson-laptop.c
+++ b/drivers/platform/loongarch/loongson-laptop.c
@@ -448,6 +448,7 @@ static int __init event_init(struct generic_sub_driver *sub_driver)
 	if (ret < 0) {
 		pr_err("Failed to setup input device keymap\n");
 		input_free_device(generic_inputdev);
+		generic_inputdev = NULL;
 
 		return ret;
 	}
@@ -502,8 +503,11 @@ static int __init generic_subdriver_init(struct generic_sub_driver *sub_driver)
 	if (ret)
 		return -EINVAL;
 
-	if (sub_driver->init)
-		sub_driver->init(sub_driver);
+	if (sub_driver->init) {
+		ret = sub_driver->init(sub_driver);
+		if (ret)
+			goto err_out;
+	}
 
 	if (sub_driver->notify) {
 		ret = setup_acpi_notify(sub_driver);
@@ -519,7 +523,7 @@ static int __init generic_subdriver_init(struct generic_sub_driver *sub_driver)
 
 err_out:
 	generic_subdriver_exit(sub_driver);
-	return (ret < 0) ? ret : 0;
+	return ret;
 }
 
 static void generic_subdriver_exit(struct generic_sub_driver *sub_driver)
-- 
2.25.1