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List: linux-kernel
Subject: Re: linux-next: dock_link_device is oopsy
From: Hillf Danton <dhillf () gmail ! com>
Date: 2012-02-18 13:37:18
Message-ID: CAJd=RBAhnsuP4+pRS=MLyOaqx8O1gOR30bcoZC0Owabh1-1nzA () mail ! gmail ! com
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On Sat, Feb 18, 2012 at 9:26 PM, Holger Macht <holger@homac.de> wrote:
> On Sa 18. Feb - 21:05:18, Hillf Danton wrote:
>> On Sat, Feb 18, 2012 at 7:14 PM, Holger Macht <holger@homac.de> wrote:
>> > So how about that?
>> >
>> > acpi: Bail out when linking devices and there are no dock stations
>> >
>> > If dock_station_count is zero, we allocate zero memory and don't check
>> > this at future references. So bail out if there are actually no dock
>> > stations.
>> >
>> > Signed-off-by: Holger Macht <holger@homac.de>
>> > ---
>> > drivers/acpi/dock.c | 19 ++++++++++++++-----
>> > 1 files changed, 14 insertions(+), 5 deletions(-)
>> >
>> > diff --git a/drivers/acpi/dock.c b/drivers/acpi/dock.c
>> > index b5e4142..0b3072c 100644
>> > --- a/drivers/acpi/dock.c
>> > +++ b/drivers/acpi/dock.c
>> > @@ -281,11 +281,15 @@ EXPORT_SYMBOL_GPL(is_dock_device);
>> > */
>> > struct device **dock_link_device(acpi_handle handle)
>> > {
>> > - struct device *dev = acpi_get_physical_device(handle);
>> > + struct device *dev;
>> > struct dock_station *dock_station;
>> > int ret, dock = 0;
>> > struct device **devices;
>> >
>> > + if (!dock_station_count)
>> > + return NULL;
>> > +
>> > + dev = acpi_get_physical_device(handle);
>> > devices = kmalloc(dock_station_count * sizeof(struct device *),
>> > GFP_KERNEL);
>> >
>> > @@ -320,12 +324,17 @@ EXPORT_SYMBOL_GPL(dock_link_device);
>> > */
>> > struct device **dock_unlink_device(acpi_handle handle)
>> > {
>> > - struct device *dev = acpi_get_physical_device(handle);
>> > + struct device *dev;
>> > struct dock_station *dock_station;
>> > int dock = 0;
>> > - struct device **devices =
>> > - kmalloc(dock_station_count * sizeof(struct device *),
>> > - GFP_KERNEL);
>> > + struct device **devices;
>> > +
>> > + if (!dock_station_count)
>> > + return NULL;
>> > +
>> > + dev = acpi_get_physical_device(handle);
>> > + devices = kmalloc(dock_station_count * sizeof(struct device *),
>> > + GFP_KERNEL);
>> >
>>
>> If bail out in this way, another patch looks needed to fix up
>> mem leakage :-(
>
> Sorry if I'm a little slow...but where is the leakage? The function
> doesn't allocate anything before bailing out in the dock_station_count
> check. And the rerun value should be freed by the caller. Please point
> me in the right direction.
>
Hi Holger
Lets check the following snippet from what you posted,
> @@ -320,12 +324,17 @@ EXPORT_SYMBOL_GPL(dock_link_device);
> */
> struct device **dock_unlink_device(acpi_handle handle)
> {
> - struct device *dev = acpi_get_physical_device(handle);
> + struct device *dev;
> struct dock_station *dock_station;
> int dock = 0;
> - struct device **devices =
> - kmalloc(dock_station_count * sizeof(struct device *),
> - GFP_KERNEL);
> + struct device **devices;
> +
> + if (!dock_station_count)
> + return NULL;
> +
> + dev = acpi_get_physical_device(handle);
> + devices = kmalloc(dock_station_count * sizeof(struct device *),
> + GFP_KERNEL);
>
> if (!dev)
> return NULL; <=== here return without freeing the newly
allocated devices after checking
dock_station_count is not zero
> --
> 1.7.7
>
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