[PATCH 3.16 281/328] pstore/ram: Fix failure-path memory leak in ramoops_init

Ben Hutchings
2018-12-09T22:02:41Z

From: Kees Cook <keescook@chromium.org>

commit bac6f6cda206ad7cbe0c73c35e494377ce9c4749 upstream.

As reported by nixiaoming, with some minor clarifications:

1) memory leak in ramoops_register_dummy():
dummy_data = kzalloc(sizeof(*dummy_data), GFP_KERNEL);
but no kfree() if platform_device_register_data() fails.

2) memory leak in ramoops_init():
Missing platform_device_unregister(dummy) and kfree(dummy_data)
if platform_driver_register(&ramoops_driver) fails.

I've clarified the purpose of ramoops_register_dummy(), and added a
common cleanup routine for all three failure paths to call.

Reported-by: nixiaoming <nixiaoming@huawei.com>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/pstore/ram.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)

--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -557,8 +557,22 @@ static struct platform_driver ramoops_dr
},
};

-static void ramoops_register_dummy(void)
+static inline void ramoops_unregister_dummy(void)
{
+ platform_device_unregister(dummy);
+ dummy = NULL;
+
+ kfree(dummy_data);
+ dummy_data = NULL;
+}
+
+static void __init ramoops_register_dummy(void)
+{
+ /*
+ * Prepare a dummy platform data structure to carry the module
+ * parameters. If mem_size isn't set, then there are no module
+ * parameters, and we can skip this.
+ */
if (!mem_size)
return;

@@ -588,21 +602,28 @@ static void ramoops_register_dummy(void)
if (IS_ERR(dummy)) {
pr_info("could not create platform device: %ld\n",
PTR_ERR(dummy));
+ dummy = NULL;
+ ramoops_unregister_dummy();
}
}

static int __init ramoops_init(void)
{
+ int ret;
+
ramoops_register_dummy();
- return platform_driver_register(&ramoops_driver);
+ ret = platform_driver_register(&ramoops_driver);
+ if (ret != 0)
+ ramoops_unregister_dummy();
+
+ return ret;
}
postcore_initcall(ramoops_init);

static void __exit ramoops_exit(void)
{
platform_driver_unregister(&ramoops_driver);
- platform_device_unregister(dummy);
- kfree(dummy_data);
+ ramoops_unregister_dummy();
}
module_exit(ramoops_exit);