2020-08-17 23:52:30

by Dmitry Osipenko

Subject: [PATCH v1] mfd: core: Fix double-free in mfd_remove_devices_fn()

The pdev.mfd_cell is released by platform_device_release(), which is
invoked by platform_device_unregister(). Hence mfd_remove_devices_fn()
shouldn't release the cell variable. The double-free bug is reported KASAN
during of MFD driver module removal.

Fixes: 466a62d7642f ("mfd: core: Make a best effort attempt to match devices with the correct of_nodes")
Signed-off-by: Dmitry Osipenko <[email protected]>
---
drivers/mfd/mfd-core.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index c3651f06684f..c50718e3db58 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -370,8 +370,6 @@ static int mfd_remove_devices_fn(struct device *dev, void *data)
regulator_bulk_unregister_supply_alias(dev, cell->parent_supplies,
cell->num_parent_supplies);

- kfree(cell);
-
platform_device_unregister(pdev);
return 0;
}
--
2.27.0

2020-08-21 14:48:05

by Lee Jones

Subject: Re: [PATCH v1] mfd: core: Fix double-free in mfd_remove_devices_fn()

On Tue, 18 Aug 2020, Dmitry Osipenko wrote:

> The pdev.mfd_cell is released by platform_device_release(), which is
> invoked by platform_device_unregister(). Hence mfd_remove_devices_fn()
> shouldn't release the cell variable. The double-free bug is reported KASAN
> during of MFD driver module removal.
>
> Fixes: 466a62d7642f ("mfd: core: Make a best effort attempt to match devices with the correct of_nodes")
> Signed-off-by: Dmitry Osipenko <[email protected]>
> ---
> drivers/mfd/mfd-core.c | 2 --
> 1 file changed, 2 deletions(-)

Applied, thanks.

--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

2020-08-24 09:36:44

by Lee Jones

Subject: Re: [PATCH v1] mfd: core: Fix double-free in mfd_remove_devices_fn()

On Mon, 24 Aug 2020, Marek Szyprowski wrote:

> Hi
>
> On 18.08.2020 01:50, Dmitry Osipenko wrote:
> > The pdev.mfd_cell is released by platform_device_release(), which is
> > invoked by platform_device_unregister(). Hence mfd_remove_devices_fn()
> > shouldn't release the cell variable. The double-free bug is reported KASAN
> > during of MFD driver module removal.
> >
> > Fixes: 466a62d7642f ("mfd: core: Make a best effort attempt to match devices with the correct of_nodes")
> > Signed-off-by: Dmitry Osipenko <[email protected]>
> > ---
>
> I've reported that almost a week earlier and got information that it
> will be dropped:
>
> https://lore.kernel.org/lkml/[email protected]/
>
> https://lore.kernel.org/lkml/20200813080100.GI4354@dell/
>
> Sadly it finally landed in v5.9-rc1. Would be nice to mention this in
> the revert:

That's true. The patch was taken out but the change managed to get in
via another commit. I will add your Reported-by to the revert.

> Reported-by: Marek Szyprowski <[email protected]>
>
> > drivers/mfd/mfd-core.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> > index c3651f06684f..c50718e3db58 100644
> > --- a/drivers/mfd/mfd-core.c
> > +++ b/drivers/mfd/mfd-core.c
> > @@ -370,8 +370,6 @@ static int mfd_remove_devices_fn(struct device *dev, void *data)
> > regulator_bulk_unregister_supply_alias(dev, cell->parent_supplies,
> > cell->num_parent_supplies);
> >
> > - kfree(cell);
> > -
> > platform_device_unregister(pdev);
> > return 0;
> > }
>
> Best regards

--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

2020-08-24 09:53:39

by Marek Szyprowski

Subject: Re: [PATCH v1] mfd: core: Fix double-free in mfd_remove_devices_fn()

Hi

On 18.08.2020 01:50, Dmitry Osipenko wrote:
> The pdev.mfd_cell is released by platform_device_release(), which is
> invoked by platform_device_unregister(). Hence mfd_remove_devices_fn()
> shouldn't release the cell variable. The double-free bug is reported KASAN
> during of MFD driver module removal.
>
> Fixes: 466a62d7642f ("mfd: core: Make a best effort attempt to match devices with the correct of_nodes")
> Signed-off-by: Dmitry Osipenko <[email protected]>
> ---

I've reported that almost a week earlier and got information that it
will be dropped:

https://lore.kernel.org/lkml/[email protected]/

https://lore.kernel.org/lkml/20200813080100.GI4354@dell/

Sadly it finally landed in v5.9-rc1. Would be nice to mention this in
the revert:

Reported-by: Marek Szyprowski <[email protected]>

> drivers/mfd/mfd-core.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index c3651f06684f..c50718e3db58 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -370,8 +370,6 @@ static int mfd_remove_devices_fn(struct device *dev, void *data)
> regulator_bulk_unregister_supply_alias(dev, cell->parent_supplies,
> cell->num_parent_supplies);
>
> - kfree(cell);
> -
> platform_device_unregister(pdev);
> return 0;
> }

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland