2022-01-14 07:59:43

by Greg Kroah-Hartman

Subject: [PATCH] moxart: fix potential use-after-free on remove path

It was reported that the mmc host structure could be accessed after it
was freed in moxart_remove(), so fix this by saving the base register of
the device and using it instead of the pointer dereference.

Cc: Ulf Hansson <[email protected]>
Cc: Xiyu Yang <[email protected]>
Cc: Xin Xiong <[email protected]>
Cc: Xin Tan <[email protected]>
Cc: Tony Lindgren <[email protected]>
Cc: Yang Li <[email protected]>
Cc: [email protected]
Cc: stable <[email protected]>
Reported-by: whitehat002 <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/mmc/host/moxart-mmc.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
index 16d1c7a43d33..f5d96940a9b8 100644
--- a/drivers/mmc/host/moxart-mmc.c
+++ b/drivers/mmc/host/moxart-mmc.c
@@ -697,6 +697,7 @@ static int moxart_remove(struct platform_device *pdev)
{
struct mmc_host *mmc = dev_get_drvdata(&pdev->dev);
struct moxart_host *host = mmc_priv(mmc);
+ void __iomem *base = host->base;

dev_set_drvdata(&pdev->dev, NULL);

@@ -707,10 +708,10 @@ static int moxart_remove(struct platform_device *pdev)
mmc_remove_host(mmc);
mmc_free_host(mmc);

- writel(0, host->base + REG_INTERRUPT_MASK);
- writel(0, host->base + REG_POWER_CONTROL);
- writel(readl(host->base + REG_CLOCK_CONTROL) | CLK_OFF,
- host->base + REG_CLOCK_CONTROL);
+ writel(0, base + REG_INTERRUPT_MASK);
+ writel(0, base + REG_POWER_CONTROL);
+ writel(readl(base + REG_CLOCK_CONTROL) | CLK_OFF,
+ base + REG_CLOCK_CONTROL);

return 0;
}
--
2.34.1

2022-01-22 01:09:14

by Ulf Hansson

Subject: Re: [PATCH] moxart: fix potential use-after-free on remove path

On Fri, 14 Jan 2022 at 08:59, Greg Kroah-Hartman
<[email protected]> wrote:
>
> It was reported that the mmc host structure could be accessed after it
> was freed in moxart_remove(), so fix this by saving the base register of
> the device and using it instead of the pointer dereference.
>
> Cc: Ulf Hansson <[email protected]>
> Cc: Xiyu Yang <[email protected]>
> Cc: Xin Xiong <[email protected]>
> Cc: Xin Tan <[email protected]>
> Cc: Tony Lindgren <[email protected]>
> Cc: Yang Li <[email protected]>
> Cc: [email protected]
> Cc: stable <[email protected]>
> Reported-by: whitehat002 <[email protected]>
> Signed-off-by: Greg Kroah-Hartman <[email protected]>
> ---
> drivers/mmc/host/moxart-mmc.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
> index 16d1c7a43d33..f5d96940a9b8 100644
> --- a/drivers/mmc/host/moxart-mmc.c
> +++ b/drivers/mmc/host/moxart-mmc.c
> @@ -697,6 +697,7 @@ static int moxart_remove(struct platform_device *pdev)
> {
> struct mmc_host *mmc = dev_get_drvdata(&pdev->dev);
> struct moxart_host *host = mmc_priv(mmc);
> + void __iomem *base = host->base;
>
> dev_set_drvdata(&pdev->dev, NULL);
>
> @@ -707,10 +708,10 @@ static int moxart_remove(struct platform_device *pdev)
> mmc_remove_host(mmc);
> mmc_free_host(mmc);
>
> - writel(0, host->base + REG_INTERRUPT_MASK);
> - writel(0, host->base + REG_POWER_CONTROL);
> - writel(readl(host->base + REG_CLOCK_CONTROL) | CLK_OFF,
> - host->base + REG_CLOCK_CONTROL);

Rather than doing it like this, I think it would be easier to move
mmc_free_host() below this part. That's usually what mmc host drivers
do clean up things in ->remove().

> + writel(0, base + REG_INTERRUPT_MASK);
> + writel(0, base + REG_POWER_CONTROL);
> + writel(readl(base + REG_CLOCK_CONTROL) | CLK_OFF,
> + base + REG_CLOCK_CONTROL);
>
> return 0;
> }

Kind regards
Uffe

2022-01-22 01:36:53

by Greg Kroah-Hartman

Subject: Re: [PATCH] moxart: fix potential use-after-free on remove path

On Fri, Jan 21, 2022 at 01:41:27PM +0100, Ulf Hansson wrote:
> On Fri, 14 Jan 2022 at 08:59, Greg Kroah-Hartman
> <[email protected]> wrote:
> >
> > It was reported that the mmc host structure could be accessed after it
> > was freed in moxart_remove(), so fix this by saving the base register of
> > the device and using it instead of the pointer dereference.
> >
> > Cc: Ulf Hansson <[email protected]>
> > Cc: Xiyu Yang <[email protected]>
> > Cc: Xin Xiong <[email protected]>
> > Cc: Xin Tan <[email protected]>
> > Cc: Tony Lindgren <[email protected]>
> > Cc: Yang Li <[email protected]>
> > Cc: [email protected]
> > Cc: stable <[email protected]>
> > Reported-by: whitehat002 <[email protected]>
> > Signed-off-by: Greg Kroah-Hartman <[email protected]>
> > ---
> > drivers/mmc/host/moxart-mmc.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
> > index 16d1c7a43d33..f5d96940a9b8 100644
> > --- a/drivers/mmc/host/moxart-mmc.c
> > +++ b/drivers/mmc/host/moxart-mmc.c
> > @@ -697,6 +697,7 @@ static int moxart_remove(struct platform_device *pdev)
> > {
> > struct mmc_host *mmc = dev_get_drvdata(&pdev->dev);
> > struct moxart_host *host = mmc_priv(mmc);
> > + void __iomem *base = host->base;
> >
> > dev_set_drvdata(&pdev->dev, NULL);
> >
> > @@ -707,10 +708,10 @@ static int moxart_remove(struct platform_device *pdev)
> > mmc_remove_host(mmc);
> > mmc_free_host(mmc);
> >
> > - writel(0, host->base + REG_INTERRUPT_MASK);
> > - writel(0, host->base + REG_POWER_CONTROL);
> > - writel(readl(host->base + REG_CLOCK_CONTROL) | CLK_OFF,
> > - host->base + REG_CLOCK_CONTROL);
>
> Rather than doing it like this, I think it would be easier to move
> mmc_free_host() below this part. That's usually what mmc host drivers
> do clean up things in ->remove().
>
> > + writel(0, base + REG_INTERRUPT_MASK);
> > + writel(0, base + REG_POWER_CONTROL);
> > + writel(readl(base + REG_CLOCK_CONTROL) | CLK_OFF,
> > + base + REG_CLOCK_CONTROL);
> >

Ok, I can do that, I didn't know if it would cause any functionality
changes, so I was trying to preserve the same logic that the driver
currently has.

Do you have this device to test this with?

thanks,

greg k-h

2022-01-22 01:42:17

by Ulf Hansson

Subject: Re: [PATCH] moxart: fix potential use-after-free on remove path

On Fri, 21 Jan 2022 at 14:54, Greg Kroah-Hartman
<[email protected]> wrote:
>
> On Fri, Jan 21, 2022 at 01:41:27PM +0100, Ulf Hansson wrote:
> > On Fri, 14 Jan 2022 at 08:59, Greg Kroah-Hartman
> > <[email protected]> wrote:
> > >
> > > It was reported that the mmc host structure could be accessed after it
> > > was freed in moxart_remove(), so fix this by saving the base register of
> > > the device and using it instead of the pointer dereference.
> > >
> > > Cc: Ulf Hansson <[email protected]>
> > > Cc: Xiyu Yang <[email protected]>
> > > Cc: Xin Xiong <[email protected]>
> > > Cc: Xin Tan <[email protected]>
> > > Cc: Tony Lindgren <[email protected]>
> > > Cc: Yang Li <[email protected]>
> > > Cc: [email protected]
> > > Cc: stable <[email protected]>
> > > Reported-by: whitehat002 <[email protected]>
> > > Signed-off-by: Greg Kroah-Hartman <[email protected]>
> > > ---
> > > drivers/mmc/host/moxart-mmc.c | 9 +++++----
> > > 1 file changed, 5 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
> > > index 16d1c7a43d33..f5d96940a9b8 100644
> > > --- a/drivers/mmc/host/moxart-mmc.c
> > > +++ b/drivers/mmc/host/moxart-mmc.c
> > > @@ -697,6 +697,7 @@ static int moxart_remove(struct platform_device *pdev)
> > > {
> > > struct mmc_host *mmc = dev_get_drvdata(&pdev->dev);
> > > struct moxart_host *host = mmc_priv(mmc);
> > > + void __iomem *base = host->base;
> > >
> > > dev_set_drvdata(&pdev->dev, NULL);
> > >
> > > @@ -707,10 +708,10 @@ static int moxart_remove(struct platform_device *pdev)
> > > mmc_remove_host(mmc);
> > > mmc_free_host(mmc);
> > >
> > > - writel(0, host->base + REG_INTERRUPT_MASK);
> > > - writel(0, host->base + REG_POWER_CONTROL);
> > > - writel(readl(host->base + REG_CLOCK_CONTROL) | CLK_OFF,
> > > - host->base + REG_CLOCK_CONTROL);
> >
> > Rather than doing it like this, I think it would be easier to move
> > mmc_free_host() below this part. That's usually what mmc host drivers
> > do clean up things in ->remove().
> >
> > > + writel(0, base + REG_INTERRUPT_MASK);
> > > + writel(0, base + REG_POWER_CONTROL);
> > > + writel(readl(base + REG_CLOCK_CONTROL) | CLK_OFF,
> > > + base + REG_CLOCK_CONTROL);
> > >
>
> Ok, I can do that, I didn't know if it would cause any functionality
> changes, so I was trying to preserve the same logic that the driver
> currently has.

Yes, but it's most likely just a simple mistake that was made by the
original author.

>
> Do you have this device to test this with?

No, I don't.

Although, I am confident that it should work fine too.

>
> thanks,
>
> greg k-h

Kind regards
Uffe

2022-01-27 14:04:06

by Greg Kroah-Hartman

Subject: Re: [PATCH] moxart: fix potential use-after-free on remove path

On Fri, Jan 21, 2022 at 03:24:05PM +0100, Ulf Hansson wrote:
> On Fri, 21 Jan 2022 at 14:54, Greg Kroah-Hartman
> <[email protected]> wrote:
> >
> > On Fri, Jan 21, 2022 at 01:41:27PM +0100, Ulf Hansson wrote:
> > > On Fri, 14 Jan 2022 at 08:59, Greg Kroah-Hartman
> > > <[email protected]> wrote:
> > > >
> > > > It was reported that the mmc host structure could be accessed after it
> > > > was freed in moxart_remove(), so fix this by saving the base register of
> > > > the device and using it instead of the pointer dereference.
> > > >
> > > > Cc: Ulf Hansson <[email protected]>
> > > > Cc: Xiyu Yang <[email protected]>
> > > > Cc: Xin Xiong <[email protected]>
> > > > Cc: Xin Tan <[email protected]>
> > > > Cc: Tony Lindgren <[email protected]>
> > > > Cc: Yang Li <[email protected]>
> > > > Cc: [email protected]
> > > > Cc: stable <[email protected]>
> > > > Reported-by: whitehat002 <[email protected]>
> > > > Signed-off-by: Greg Kroah-Hartman <[email protected]>
> > > > ---
> > > > drivers/mmc/host/moxart-mmc.c | 9 +++++----
> > > > 1 file changed, 5 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
> > > > index 16d1c7a43d33..f5d96940a9b8 100644
> > > > --- a/drivers/mmc/host/moxart-mmc.c
> > > > +++ b/drivers/mmc/host/moxart-mmc.c
> > > > @@ -697,6 +697,7 @@ static int moxart_remove(struct platform_device *pdev)
> > > > {
> > > > struct mmc_host *mmc = dev_get_drvdata(&pdev->dev);
> > > > struct moxart_host *host = mmc_priv(mmc);
> > > > + void __iomem *base = host->base;
> > > >
> > > > dev_set_drvdata(&pdev->dev, NULL);
> > > >
> > > > @@ -707,10 +708,10 @@ static int moxart_remove(struct platform_device *pdev)
> > > > mmc_remove_host(mmc);
> > > > mmc_free_host(mmc);
> > > >
> > > > - writel(0, host->base + REG_INTERRUPT_MASK);
> > > > - writel(0, host->base + REG_POWER_CONTROL);
> > > > - writel(readl(host->base + REG_CLOCK_CONTROL) | CLK_OFF,
> > > > - host->base + REG_CLOCK_CONTROL);
> > >
> > > Rather than doing it like this, I think it would be easier to move
> > > mmc_free_host() below this part. That's usually what mmc host drivers
> > > do clean up things in ->remove().
> > >
> > > > + writel(0, base + REG_INTERRUPT_MASK);
> > > > + writel(0, base + REG_POWER_CONTROL);
> > > > + writel(readl(base + REG_CLOCK_CONTROL) | CLK_OFF,
> > > > + base + REG_CLOCK_CONTROL);
> > > >
> >
> > Ok, I can do that, I didn't know if it would cause any functionality
> > changes, so I was trying to preserve the same logic that the driver
> > currently has.
>
> Yes, but it's most likely just a simple mistake that was made by the
> original author.
>
> >
> > Do you have this device to test this with?
>
> No, I don't.
>
> Although, I am confident that it should work fine too.

Great, now sent v2:
https://lore.kernel.org/r/[email protected]