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SubjectRe: [PATCH] acpi: Fix use-after-free in acpi_ipmi.c
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Hi,
On 11/25/2020 11:53 PM, Rafael J. Wysocki wrote:
> On Tue, Nov 24, 2020 at 1:51 PM Youling Tang <tangyouling@loongson.cn> wrote:
>> kfree() has been called inside put_device so anther kfree would cause a
>> use-after-free bug.
>>
>> Signed-off-by: Youling Tang <tangyouling@loongson.cn>
>> ---
>> drivers/acpi/acpi_ipmi.c | 2 --
>> 1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/acpi/acpi_ipmi.c b/drivers/acpi/acpi_ipmi.c
>> index 9d6c0fc..72902b6 100644
>> --- a/drivers/acpi/acpi_ipmi.c
>> +++ b/drivers/acpi/acpi_ipmi.c
>> @@ -130,7 +130,6 @@ ipmi_dev_alloc(int iface, struct device *dev, acpi_handle handle)
>> ipmi_device, &user);
>> if (err) {
>> put_device(dev);
>> - kfree(ipmi_device);
> dev doesn't point to the same object in memory as ipmi_device, though,
> if I'm not mistaken.
>
> Please double check that and resend the patch if you are sure that it
> is correct.
You're right, dev really doesn't point to the same memory object
as ipmi_device. I'll send v2 later.

Thanks,
Youling.
>> return NULL;
>> }
>> ipmi_device->user_interface = user;
>> @@ -142,7 +141,6 @@ static void ipmi_dev_release(struct acpi_ipmi_device *ipmi_device)
>> {
>> ipmi_destroy_user(ipmi_device->user_interface);
>> put_device(ipmi_device->dev);
>> - kfree(ipmi_device);
>> }
>>
>> static void ipmi_dev_release_kref(struct kref *kref)
>> --
>> 2.1.0
>>

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