linux-kernel - [PATCH] lib/test_kmod: Fix a use after free in register_test_dev

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Date:   Thu, 11 Mar 2021 00:02:46 -0800
From:   Lv Yunlong <lyl2019@...l.ustc.edu.cn>
To:     mcgrof@...nel.org
Cc:     linux-kernel@...r.kernel.org, Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Subject: [PATCH] lib/test_kmod: Fix a use after free in register_test_dev_kmod

In register_test_dev_kmod, it calls free_test_dev_kmod() to free
test_dev. But free_test_dev_kmod() can't set the original pointer
test_dev to NULL, because the test_dev was passed by it's value
not reference.

Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
---
 lib/test_kmod.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/test_kmod.c b/lib/test_kmod.c
index 38c250fbace3..aa8a2a563d7e 100644
--- a/lib/test_kmod.c
+++ b/lib/test_kmod.c
@@ -1124,7 +1124,6 @@ static void free_test_dev_kmod(struct kmod_test_device *test_dev)
 		free_test_dev_info(test_dev);
 		kmod_config_free(test_dev);
 		vfree(test_dev);
-		test_dev = NULL;
 	}
 }
 
@@ -1149,6 +1148,7 @@ static struct kmod_test_device *register_test_dev_kmod(void)
 	if (ret) {
 		pr_err("could not register misc device: %d\n", ret);
 		free_test_dev_kmod(test_dev);
+		test_dev = NULL;
 		goto out;
 	}
 
-- 
2.25.1