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* [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
@ 2022-03-03  1:30 Jianglei Nie
  2022-03-03  1:44 ` Cai,Huoqing
  2022-03-03 16:04 ` Jakub Kicinski
  0 siblings, 2 replies; 7+ messages in thread
From: Jianglei Nie @ 2022-03-03  1:30 UTC (permalink / raw)
  To: davem, kuba, caihuoqing; +Cc: netdev, linux-kernel, Jianglei Nie

If bus->state is equal to MDIOBUS_ALLOCATED, mdiobus_free(bus) will free
the "bus". But bus->name is still used in the next line, which will lead
to a use after free.

We can fix it by assigning dev_err_probe() to dev_err before the bus is
freed to avoid the uaf.

Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
---
 drivers/net/ethernet/arc/emac_mdio.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/arc/emac_mdio.c b/drivers/net/ethernet/arc/emac_mdio.c
index 9acf589b1178..795a25c5848a 100644
--- a/drivers/net/ethernet/arc/emac_mdio.c
+++ b/drivers/net/ethernet/arc/emac_mdio.c
@@ -165,9 +165,10 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
 
 	error = of_mdiobus_register(bus, priv->dev->of_node);
 	if (error) {
-		mdiobus_free(bus);
-		return dev_err_probe(priv->dev, error,
+		int dev_err = dev_err_probe(priv->dev, error,
 				     "cannot register MDIO bus %s\n", bus->name);
+		mdiobus_free(bus);
+		return dev_err;
 	}
 
 	return 0;
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread

* RE: [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
  2022-03-03  1:30 [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe() Jianglei Nie
@ 2022-03-03  1:44 ` Cai,Huoqing
  2022-03-03 16:04 ` Jakub Kicinski
  1 sibling, 0 replies; 7+ messages in thread
From: Cai,Huoqing @ 2022-03-03  1:44 UTC (permalink / raw)
  To: Jianglei Nie, davem, kuba; +Cc: netdev, linux-kernel

Hello,

> -----Original Message-----
> From: Jianglei Nie <niejianglei2021@163.com>
> Sent: 2022年3月3日 9:30
> To: davem@davemloft.net; kuba@kernel.org; Cai,Huoqing
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Jianglei Nie
> Subject: [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
> 
> If bus->state is equal to MDIOBUS_ALLOCATED, mdiobus_free(bus) will free
> the "bus". But bus->name is still used in the next line, which will lead
> to a use after free.
> 
> We can fix it by assigning dev_err_probe() to dev_err before the bus is
> freed to avoid the uaf.
Add fix log here:)
Fixes: 95b5fc03c189 ("net: arc_emac: Make use of the helper function dev_err_probe()")
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> ---
>  drivers/net/ethernet/arc/emac_mdio.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/arc/emac_mdio.c
> b/drivers/net/ethernet/arc/emac_mdio.c
> index 9acf589b1178..795a25c5848a 100644
> --- a/drivers/net/ethernet/arc/emac_mdio.c
> +++ b/drivers/net/ethernet/arc/emac_mdio.c
> @@ -165,9 +165,10 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
> 
>  	error = of_mdiobus_register(bus, priv->dev->of_node);
>  	if (error) {
> -		mdiobus_free(bus);
> -		return dev_err_probe(priv->dev, error,
> +		int dev_err = dev_err_probe(priv->dev, error,
>  				     "cannot register MDIO bus %s\n", bus-
> >name);
> +		mdiobus_free(bus);
> +		return dev_err;
>  	}
> 
>  	return 0;
> --
> 2.25.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
  2022-03-03  1:30 [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe() Jianglei Nie
  2022-03-03  1:44 ` Cai,Huoqing
@ 2022-03-03 16:04 ` Jakub Kicinski
  1 sibling, 0 replies; 7+ messages in thread
From: Jakub Kicinski @ 2022-03-03 16:04 UTC (permalink / raw)
  To: Jianglei Nie; +Cc: davem, caihuoqing, netdev, linux-kernel

On Thu,  3 Mar 2022 09:30:22 +0800 Jianglei Nie wrote:
> If bus->state is equal to MDIOBUS_ALLOCATED, mdiobus_free(bus) will free
> the "bus". But bus->name is still used in the next line, which will lead
> to a use after free.
> 
> We can fix it by assigning dev_err_probe() to dev_err before the bus is
> freed to avoid the uaf.
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> ---
>  drivers/net/ethernet/arc/emac_mdio.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/arc/emac_mdio.c b/drivers/net/ethernet/arc/emac_mdio.c
> index 9acf589b1178..795a25c5848a 100644
> --- a/drivers/net/ethernet/arc/emac_mdio.c
> +++ b/drivers/net/ethernet/arc/emac_mdio.c
> @@ -165,9 +165,10 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
>  
>  	error = of_mdiobus_register(bus, priv->dev->of_node);
>  	if (error) {
> -		mdiobus_free(bus);
> -		return dev_err_probe(priv->dev, error,
> +		int dev_err = dev_err_probe(priv->dev, error,
>  				     "cannot register MDIO bus %s\n", bus->name);

Bus name is a constant please put it in a local variable:

	const char *name = "Synopsys MII Bus";

	...
	bus->name = name;

and then you can use name in the error message without referring to bus.

> +		mdiobus_free(bus);
> +		return dev_err;
>  	}
>  
>  	return 0;


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
  2022-03-08 13:50   ` Cai,Huoqing
@ 2022-03-08 13:57     ` Andrew Lunn
  0 siblings, 0 replies; 7+ messages in thread
From: Andrew Lunn @ 2022-03-08 13:57 UTC (permalink / raw)
  To: Cai,Huoqing; +Cc: Jianglei Nie, davem, kuba, netdev, linux-kernel

> If resend a patch,  you can use prefix "[PATCH v2]" in subject.
> e.g.  git format-patch -1 -v2

Yes.

But please also read the netdev FAQ:

https://docs.kernel.org/networking/netdev-FAQ.html

	Andrew

^ permalink raw reply	[flat|nested] 7+ messages in thread

* RE: [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
  2022-03-08 13:42 ` Andrew Lunn
@ 2022-03-08 13:50   ` Cai,Huoqing
  2022-03-08 13:57     ` Andrew Lunn
  0 siblings, 1 reply; 7+ messages in thread
From: Cai,Huoqing @ 2022-03-08 13:50 UTC (permalink / raw)
  To: Andrew Lunn, Jianglei Nie; +Cc: davem, kuba, netdev, linux-kernel

Hello,

> -----Original Message-----
> From: Andrew Lunn <andrew@lunn.ch>
> Sent: 2022年3月8日 21:43
> To: Jianglei Nie
> Cc: davem@davemloft.net; kuba@kernel.org; Cai,Huoqing;
> netdev@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
If resend a patch,  you can use prefix "[PATCH v2]" in subject.
e.g.  git format-patch -1 -v2
> 
> On Tue, Mar 08, 2022 at 07:10:05PM +0800, Jianglei Nie wrote:
> > If bus->state is equal to MDIOBUS_ALLOCATED, mdiobus_free(bus) will
> free
> > the "bus". But bus->name is still used in the next line, which will lead
> > to a use after free.
> >
> > We can fix it by putting the bus->name in a local variable and then use
> > the name in the error message without referring to bus to avoid the uaf.
> >
> > Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> > ---
> >  drivers/net/ethernet/arc/emac_mdio.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/arc/emac_mdio.c
> b/drivers/net/ethernet/arc/emac_mdio.c
> > index 9acf589b1178..33fd63d227ef 100644
> > --- a/drivers/net/ethernet/arc/emac_mdio.c
> > +++ b/drivers/net/ethernet/arc/emac_mdio.c
> > @@ -134,6 +134,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
> >  	struct device_node *np = priv->dev->of_node;
> >  	struct mii_bus *bus;
> >  	int error;
> > +	const char *name = "Synopsys MII Bus";
> 
> Netdev uses reverse christmass tree, meaning you need to sort
> variables longest to shortest.
> 
> I'm also wondering about the lifetime of name. name itself is a stack
> variable, so it will disappear as soon as the function exits. The
> string itself is in the rodata section. But is a copy made onto the
> stack, or does bus->name point to the rodata?
> 
>        Andrew
> 
> >  	bus = mdiobus_alloc();
> >  	if (!bus)
> > @@ -142,7 +143,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
> >  	priv->bus = bus;
> >  	bus->priv = priv;
> >  	bus->parent = priv->dev;
> > -	bus->name = "Synopsys MII Bus";
> > +	bus->name = name;
> >  	bus->read = &arc_mdio_read;
> >  	bus->write = &arc_mdio_write;
> >  	bus->reset = &arc_mdio_reset;
> > @@ -167,7 +168,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
> >  	if (error) {
> >  		mdiobus_free(bus);
> >  		return dev_err_probe(priv->dev, error,
> > -				     "cannot register MDIO bus %s\n", bus-
> >name);
> > +				     "cannot register MDIO bus %s\n", name);
> >  	}
> >
> >  	return 0;
> > --
> > 2.25.1
> >

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
  2022-03-08 11:10 Jianglei Nie
@ 2022-03-08 13:42 ` Andrew Lunn
  2022-03-08 13:50   ` Cai,Huoqing
  0 siblings, 1 reply; 7+ messages in thread
From: Andrew Lunn @ 2022-03-08 13:42 UTC (permalink / raw)
  To: Jianglei Nie; +Cc: davem, kuba, caihuoqing, netdev, linux-kernel

On Tue, Mar 08, 2022 at 07:10:05PM +0800, Jianglei Nie wrote:
> If bus->state is equal to MDIOBUS_ALLOCATED, mdiobus_free(bus) will free
> the "bus". But bus->name is still used in the next line, which will lead
> to a use after free.
> 
> We can fix it by putting the bus->name in a local variable and then use
> the name in the error message without referring to bus to avoid the uaf.
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> ---
>  drivers/net/ethernet/arc/emac_mdio.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/arc/emac_mdio.c b/drivers/net/ethernet/arc/emac_mdio.c
> index 9acf589b1178..33fd63d227ef 100644
> --- a/drivers/net/ethernet/arc/emac_mdio.c
> +++ b/drivers/net/ethernet/arc/emac_mdio.c
> @@ -134,6 +134,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
>  	struct device_node *np = priv->dev->of_node;
>  	struct mii_bus *bus;
>  	int error;
> +	const char *name = "Synopsys MII Bus";

Netdev uses reverse christmass tree, meaning you need to sort
variables longest to shortest.

I'm also wondering about the lifetime of name. name itself is a stack
variable, so it will disappear as soon as the function exits. The
string itself is in the rodata section. But is a copy made onto the
stack, or does bus->name point to the rodata?

       Andrew

>  	bus = mdiobus_alloc();
>  	if (!bus)
> @@ -142,7 +143,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
>  	priv->bus = bus;
>  	bus->priv = priv;
>  	bus->parent = priv->dev;
> -	bus->name = "Synopsys MII Bus";
> +	bus->name = name;
>  	bus->read = &arc_mdio_read;
>  	bus->write = &arc_mdio_write;
>  	bus->reset = &arc_mdio_reset;
> @@ -167,7 +168,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
>  	if (error) {
>  		mdiobus_free(bus);
>  		return dev_err_probe(priv->dev, error,
> -				     "cannot register MDIO bus %s\n", bus->name);
> +				     "cannot register MDIO bus %s\n", name);
>  	}
>  
>  	return 0;
> -- 
> 2.25.1
> 

^ permalink raw reply	[flat|nested] 7+ messages in thread

* [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe()
@ 2022-03-08 11:10 Jianglei Nie
  2022-03-08 13:42 ` Andrew Lunn
  0 siblings, 1 reply; 7+ messages in thread
From: Jianglei Nie @ 2022-03-08 11:10 UTC (permalink / raw)
  To: davem, kuba, caihuoqing; +Cc: netdev, linux-kernel, Jianglei Nie

If bus->state is equal to MDIOBUS_ALLOCATED, mdiobus_free(bus) will free
the "bus". But bus->name is still used in the next line, which will lead
to a use after free.

We can fix it by putting the bus->name in a local variable and then use
the name in the error message without referring to bus to avoid the uaf.

Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
---
 drivers/net/ethernet/arc/emac_mdio.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/arc/emac_mdio.c b/drivers/net/ethernet/arc/emac_mdio.c
index 9acf589b1178..33fd63d227ef 100644
--- a/drivers/net/ethernet/arc/emac_mdio.c
+++ b/drivers/net/ethernet/arc/emac_mdio.c
@@ -134,6 +134,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
 	struct device_node *np = priv->dev->of_node;
 	struct mii_bus *bus;
 	int error;
+	const char *name = "Synopsys MII Bus";
 
 	bus = mdiobus_alloc();
 	if (!bus)
@@ -142,7 +143,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
 	priv->bus = bus;
 	bus->priv = priv;
 	bus->parent = priv->dev;
-	bus->name = "Synopsys MII Bus";
+	bus->name = name;
 	bus->read = &arc_mdio_read;
 	bus->write = &arc_mdio_write;
 	bus->reset = &arc_mdio_reset;
@@ -167,7 +168,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
 	if (error) {
 		mdiobus_free(bus);
 		return dev_err_probe(priv->dev, error,
-				     "cannot register MDIO bus %s\n", bus->name);
+				     "cannot register MDIO bus %s\n", name);
 	}
 
 	return 0;
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2022-03-08 14:06 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-03-03  1:30 [PATCH] net: arc_emac: Fix use after free in arc_mdio_probe() Jianglei Nie
2022-03-03  1:44 ` Cai,Huoqing
2022-03-03 16:04 ` Jakub Kicinski
2022-03-08 11:10 Jianglei Nie
2022-03-08 13:42 ` Andrew Lunn
2022-03-08 13:50   ` Cai,Huoqing
2022-03-08 13:57     ` Andrew Lunn

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