[PATCH net] gtp: fix an use-before-init in gtp_newlink()

[PATCH net] gtp: fix an use-before-init in gtp_newlink()

[Masahiro Fujiwara]

*_pdp_find() from gtp_encap_recv() would trigger a crash when a peer
sends GTP packets while creating new GTP device.

RIP: 0010:gtp1_pdp_find.isra.0+0x68/0x90 [gtp]
<SNIP>
Call Trace:
 <IRQ>
 gtp_encap_recv+0xc2/0x2e0 [gtp]
 ? gtp1_pdp_find.isra.0+0x90/0x90 [gtp]
 udp_queue_rcv_one_skb+0x1fe/0x530
 udp_queue_rcv_skb+0x40/0x1b0
 udp_unicast_rcv_skb.isra.0+0x78/0x90
 __udp4_lib_rcv+0x5af/0xc70
 udp_rcv+0x1a/0x20
 ip_protocol_deliver_rcu+0xc5/0x1b0
 ip_local_deliver_finish+0x48/0x50
 ip_local_deliver+0xe5/0xf0
 ? ip_protocol_deliver_rcu+0x1b0/0x1b0

gtp_encap_enable() should be called after gtp_hastable_new() otherwise
*_pdp_find() will access the uninitialized hash table.

Fixes: 1e3a3abd8 ("gtp: make GTP sockets in gtp_newlink optional")
Signed-off-by: Masahiro Fujiwara <fujiwara.masahiro@gmail.com>
---
 drivers/net/gtp.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 8e47d0112e5d..6c56337b02a3 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -663,10 +663,6 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	gtp = netdev_priv(dev);
 
-	err = gtp_encap_enable(gtp, data);
-	if (err < 0)
-		return err;
-
 	if (!data[IFLA_GTP_PDP_HASHSIZE]) {
 		hashsize = 1024;
 	} else {
@@ -676,13 +672,18 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 	}
 
 	err = gtp_hashtable_new(gtp, hashsize);
+	if (err < 0) {
+		return err;
+	}
+
+	err = gtp_encap_enable(gtp, data);
 	if (err < 0)
 		goto out_encap;
 
 	err = register_netdevice(dev);
 	if (err < 0) {
 		netdev_dbg(dev, "failed to register new netdev %d\n", err);
-		goto out_hashtable;
+		goto out_encap;
 	}
 
 	gn = net_generic(dev_net(dev), gtp_net_id);
@@ -693,11 +694,10 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	return 0;
 
-out_hashtable:
-	kfree(gtp->addr_hash);
-	kfree(gtp->tid_hash);
 out_encap:
 	gtp_encap_disable(gtp);
+	kfree(gtp->addr_hash);
+	kfree(gtp->tid_hash);
 	return err;
 }
 
-- 
2.24.3

Re: [PATCH net] gtp: fix an use-before-init in gtp_newlink()

[Jakub Kicinski]

On Sat, 24 Oct 2020 15:42:33 +0000 Masahiro Fujiwara wrote:
> *_pdp_find() from gtp_encap_recv() would trigger a crash when a peer
> sends GTP packets while creating new GTP device.
> 
> RIP: 0010:gtp1_pdp_find.isra.0+0x68/0x90 [gtp]
> <SNIP>
> Call Trace:
>  <IRQ>
>  gtp_encap_recv+0xc2/0x2e0 [gtp]
>  ? gtp1_pdp_find.isra.0+0x90/0x90 [gtp]
>  udp_queue_rcv_one_skb+0x1fe/0x530
>  udp_queue_rcv_skb+0x40/0x1b0
>  udp_unicast_rcv_skb.isra.0+0x78/0x90
>  __udp4_lib_rcv+0x5af/0xc70
>  udp_rcv+0x1a/0x20
>  ip_protocol_deliver_rcu+0xc5/0x1b0
>  ip_local_deliver_finish+0x48/0x50
>  ip_local_deliver+0xe5/0xf0
>  ? ip_protocol_deliver_rcu+0x1b0/0x1b0
> 
> gtp_encap_enable() should be called after gtp_hastable_new() otherwise
> *_pdp_find() will access the uninitialized hash table.

Looks good, minor nits:
 
 - is the time zone broken on your system? Looks like your email has
   arrived with the date far in the past, so the build systems have
   missed it. Could you double check the time on your system?

> Fixes: 1e3a3abd8 ("gtp: make GTP sockets in gtp_newlink optional")

The hash looks short, should be at lest 12 chars:

Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional")

> Signed-off-by: Masahiro Fujiwara <fujiwara.masahiro@gmail.com>

> diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
> index 8e47d0112e5d..6c56337b02a3 100644
> --- a/drivers/net/gtp.c
> +++ b/drivers/net/gtp.c
> @@ -663,10 +663,6 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
>  
>  	gtp = netdev_priv(dev);
>  
> -	err = gtp_encap_enable(gtp, data);
> -	if (err < 0)
> -		return err;
> -
>  	if (!data[IFLA_GTP_PDP_HASHSIZE]) {
>  		hashsize = 1024;
>  	} else {
> @@ -676,13 +672,18 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
>  	}
>  
>  	err = gtp_hashtable_new(gtp, hashsize);
> +	if (err < 0) {
> +		return err;
> +	}

no need for braces around single statement

> +
> +	err = gtp_encap_enable(gtp, data);
>  	if (err < 0)
>  		goto out_encap;
>  
>  	err = register_netdevice(dev);
>  	if (err < 0) {
>  		netdev_dbg(dev, "failed to register new netdev %d\n", err);
> -		goto out_hashtable;
> +		goto out_encap;
>  	}
>  
>  	gn = net_generic(dev_net(dev), gtp_net_id);
> @@ -693,11 +694,10 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
>  
>  	return 0;
>  
> -out_hashtable:
> -	kfree(gtp->addr_hash);
> -	kfree(gtp->tid_hash);
>  out_encap:
>  	gtp_encap_disable(gtp);

I'd personally move the out_hashtable: label here and keep it, just for
clarity. Otherwise reader has to double check that gtp_encap_disable()
can be safely called before gtp_encap_enable().

Also gtp_encap_disable() could change in the future breaking this
assumption.

> +	kfree(gtp->addr_hash);
> +	kfree(gtp->tid_hash);
>  	return err;
>  }
>  

Re: [PATCH net] gtp: fix an use-before-init in gtp_newlink()

[Masahiro Fujiwara]

Hi,

Thanks for the review. Will send a new patch with the fixes soon.

----
Fujiwara

On Mon, Oct 26, 2020 at 6:05 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Sat, 24 Oct 2020 15:42:33 +0000 Masahiro Fujiwara wrote:
> > *_pdp_find() from gtp_encap_recv() would trigger a crash when a peer
> > sends GTP packets while creating new GTP device.
> >
> > RIP: 0010:gtp1_pdp_find.isra.0+0x68/0x90 [gtp]
> > <SNIP>
> > Call Trace:
> >  <IRQ>
> >  gtp_encap_recv+0xc2/0x2e0 [gtp]
> >  ? gtp1_pdp_find.isra.0+0x90/0x90 [gtp]
> >  udp_queue_rcv_one_skb+0x1fe/0x530
> >  udp_queue_rcv_skb+0x40/0x1b0
> >  udp_unicast_rcv_skb.isra.0+0x78/0x90
> >  __udp4_lib_rcv+0x5af/0xc70
> >  udp_rcv+0x1a/0x20
> >  ip_protocol_deliver_rcu+0xc5/0x1b0
> >  ip_local_deliver_finish+0x48/0x50
> >  ip_local_deliver+0xe5/0xf0
> >  ? ip_protocol_deliver_rcu+0x1b0/0x1b0
> >
> > gtp_encap_enable() should be called after gtp_hastable_new() otherwise
> > *_pdp_find() will access the uninitialized hash table.
>
> Looks good, minor nits:
>
>  - is the time zone broken on your system? Looks like your email has
>    arrived with the date far in the past, so the build systems have
>    missed it. Could you double check the time on your system?
>
> > Fixes: 1e3a3abd8 ("gtp: make GTP sockets in gtp_newlink optional")
>
> The hash looks short, should be at lest 12 chars:
>
> Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional")
>
> > Signed-off-by: Masahiro Fujiwara <fujiwara.masahiro@gmail.com>
>
> > diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
> > index 8e47d0112e5d..6c56337b02a3 100644
> > --- a/drivers/net/gtp.c
> > +++ b/drivers/net/gtp.c
> > @@ -663,10 +663,6 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
> >
> >       gtp = netdev_priv(dev);
> >
> > -     err = gtp_encap_enable(gtp, data);
> > -     if (err < 0)
> > -             return err;
> > -
> >       if (!data[IFLA_GTP_PDP_HASHSIZE]) {
> >               hashsize = 1024;
> >       } else {
> > @@ -676,13 +672,18 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
> >       }
> >
> >       err = gtp_hashtable_new(gtp, hashsize);
> > +     if (err < 0) {
> > +             return err;
> > +     }
>
> no need for braces around single statement
>
> > +
> > +     err = gtp_encap_enable(gtp, data);
> >       if (err < 0)
> >               goto out_encap;
> >
> >       err = register_netdevice(dev);
> >       if (err < 0) {
> >               netdev_dbg(dev, "failed to register new netdev %d\n", err);
> > -             goto out_hashtable;
> > +             goto out_encap;
> >       }
> >
> >       gn = net_generic(dev_net(dev), gtp_net_id);
> > @@ -693,11 +694,10 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
> >
> >       return 0;
> >
> > -out_hashtable:
> > -     kfree(gtp->addr_hash);
> > -     kfree(gtp->tid_hash);
> >  out_encap:
> >       gtp_encap_disable(gtp);
>
> I'd personally move the out_hashtable: label here and keep it, just for
> clarity. Otherwise reader has to double check that gtp_encap_disable()
> can be safely called before gtp_encap_enable().
>
> Also gtp_encap_disable() could change in the future breaking this
> assumption.
>
> > +     kfree(gtp->addr_hash);
> > +     kfree(gtp->tid_hash);
> >       return err;
> >  }
> >
>

[PATCH v2 net] gtp: fix an use-before-init in gtp_newlink()

[Masahiro Fujiwara]

*_pdp_find() from gtp_encap_recv() would trigger a crash when a peer
sends GTP packets while creating new GTP device.

RIP: 0010:gtp1_pdp_find.isra.0+0x68/0x90 [gtp]
<SNIP>
Call Trace:
 <IRQ>
 gtp_encap_recv+0xc2/0x2e0 [gtp]
 ? gtp1_pdp_find.isra.0+0x90/0x90 [gtp]
 udp_queue_rcv_one_skb+0x1fe/0x530
 udp_queue_rcv_skb+0x40/0x1b0
 udp_unicast_rcv_skb.isra.0+0x78/0x90
 __udp4_lib_rcv+0x5af/0xc70
 udp_rcv+0x1a/0x20
 ip_protocol_deliver_rcu+0xc5/0x1b0
 ip_local_deliver_finish+0x48/0x50
 ip_local_deliver+0xe5/0xf0
 ? ip_protocol_deliver_rcu+0x1b0/0x1b0

gtp_encap_enable() should be called after gtp_hastable_new() otherwise
*_pdp_find() will access the uninitialized hash table.

Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional")
Signed-off-by: Masahiro Fujiwara <fujiwara.masahiro@gmail.com>
---
v2:
 - leave out_hashtable: label for clarity (Jakub).
 - fix code and comment styles.

 drivers/net/gtp.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 8e47d0112e5d..07cb6d9495e8 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -663,10 +663,6 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	gtp = netdev_priv(dev);
 
-	err = gtp_encap_enable(gtp, data);
-	if (err < 0)
-		return err;
-
 	if (!data[IFLA_GTP_PDP_HASHSIZE]) {
 		hashsize = 1024;
 	} else {
@@ -676,13 +672,17 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 	}
 
 	err = gtp_hashtable_new(gtp, hashsize);
+	if (err < 0)
+		return err;
+
+	err = gtp_encap_enable(gtp, data);
 	if (err < 0)
 		goto out_encap;
 
 	err = register_netdevice(dev);
 	if (err < 0) {
 		netdev_dbg(dev, "failed to register new netdev %d\n", err);
-		goto out_hashtable;
+		goto out_encap;
 	}
 
 	gn = net_generic(dev_net(dev), gtp_net_id);
@@ -693,11 +693,11 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	return 0;
 
+out_encap:
+	gtp_encap_disable(gtp);
 out_hashtable:
 	kfree(gtp->addr_hash);
 	kfree(gtp->tid_hash);
-out_encap:
-	gtp_encap_disable(gtp);
 	return err;
 }
 
-- 
2.24.3

Re: [PATCH v2 net] gtp: fix an use-before-init in gtp_newlink()

[Jakub Kicinski]

On Mon, 26 Oct 2020 16:22:27 +0900 Masahiro Fujiwara wrote:
> v2:
>  - leave out_hashtable: label for clarity (Jakub).
>  - fix code and comment styles.

Thanks!

> diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
> index 8e47d0112e5d..07cb6d9495e8 100644
> --- a/drivers/net/gtp.c
> +++ b/drivers/net/gtp.c
> @@ -663,10 +663,6 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
>  
>  	gtp = netdev_priv(dev);
>  
> -	err = gtp_encap_enable(gtp, data);
> -	if (err < 0)
> -		return err;
> -
>  	if (!data[IFLA_GTP_PDP_HASHSIZE]) {
>  		hashsize = 1024;
>  	} else {
> @@ -676,13 +672,17 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
>  	}
>  
>  	err = gtp_hashtable_new(gtp, hashsize);
> +	if (err < 0)
> +		return err;
> +
> +	err = gtp_encap_enable(gtp, data);
>  	if (err < 0)
>  		goto out_encap;

This needs to say goto out_hashtable; now.

[PATCH v3] gtp: fix an use-before-init in gtp_newlink()

[Masahiro Fujiwara]

*_pdp_find() from gtp_encap_recv() would trigger a crash when a peer
sends GTP packets while creating new GTP device.

RIP: 0010:gtp1_pdp_find.isra.0+0x68/0x90 [gtp]
<SNIP>
Call Trace:
 <IRQ>
 gtp_encap_recv+0xc2/0x2e0 [gtp]
 ? gtp1_pdp_find.isra.0+0x90/0x90 [gtp]
 udp_queue_rcv_one_skb+0x1fe/0x530
 udp_queue_rcv_skb+0x40/0x1b0
 udp_unicast_rcv_skb.isra.0+0x78/0x90
 __udp4_lib_rcv+0x5af/0xc70
 udp_rcv+0x1a/0x20
 ip_protocol_deliver_rcu+0xc5/0x1b0
 ip_local_deliver_finish+0x48/0x50
 ip_local_deliver+0xe5/0xf0
 ? ip_protocol_deliver_rcu+0x1b0/0x1b0

gtp_encap_enable() should be called after gtp_hastable_new() otherwise
*_pdp_find() will access the uninitialized hash table.

v2:
 - Leave out_hashtable: label for clarity (Jakub).
 - Fix code and comment styles.

Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional")
Signed-off-by: Masahiro Fujiwara <fujiwara.masahiro@gmail.com>
---
v3:
 - Fix goto err label.

 drivers/net/gtp.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 8e47d0112e5d..10f910f8cbe5 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -663,10 +663,6 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	gtp = netdev_priv(dev);
 
-	err = gtp_encap_enable(gtp, data);
-	if (err < 0)
-		return err;
-
 	if (!data[IFLA_GTP_PDP_HASHSIZE]) {
 		hashsize = 1024;
 	} else {
@@ -677,12 +673,16 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	err = gtp_hashtable_new(gtp, hashsize);
 	if (err < 0)
-		goto out_encap;
+		return err;
+
+	err = gtp_encap_enable(gtp, data);
+	if (err < 0)
+		goto out_hashtable;
 
 	err = register_netdevice(dev);
 	if (err < 0) {
 		netdev_dbg(dev, "failed to register new netdev %d\n", err);
-		goto out_hashtable;
+		goto out_encap;
 	}
 
 	gn = net_generic(dev_net(dev), gtp_net_id);
@@ -693,11 +693,11 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	return 0;
 
+out_encap:
+	gtp_encap_disable(gtp);
 out_hashtable:
 	kfree(gtp->addr_hash);
 	kfree(gtp->tid_hash);
-out_encap:
-	gtp_encap_disable(gtp);
 	return err;
 }
 
-- 
2.24.3

[PATCH v3 net] gtp: fix an use-before-init in gtp_newlink()

[Masahiro Fujiwara]

*_pdp_find() from gtp_encap_recv() would trigger a crash when a peer
sends GTP packets while creating new GTP device.

RIP: 0010:gtp1_pdp_find.isra.0+0x68/0x90 [gtp]
<SNIP>
Call Trace:
 <IRQ>
 gtp_encap_recv+0xc2/0x2e0 [gtp]
 ? gtp1_pdp_find.isra.0+0x90/0x90 [gtp]
 udp_queue_rcv_one_skb+0x1fe/0x530
 udp_queue_rcv_skb+0x40/0x1b0
 udp_unicast_rcv_skb.isra.0+0x78/0x90
 __udp4_lib_rcv+0x5af/0xc70
 udp_rcv+0x1a/0x20
 ip_protocol_deliver_rcu+0xc5/0x1b0
 ip_local_deliver_finish+0x48/0x50
 ip_local_deliver+0xe5/0xf0
 ? ip_protocol_deliver_rcu+0x1b0/0x1b0

gtp_encap_enable() should be called after gtp_hastable_new() otherwise
*_pdp_find() will access the uninitialized hash table.

Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional")
Signed-off-by: Masahiro Fujiwara <fujiwara.masahiro@gmail.com>
---
v3:
 - Fix goto err label.

 drivers/net/gtp.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 8e47d0112e5d..10f910f8cbe5 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -663,10 +663,6 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	gtp = netdev_priv(dev);
 
-	err = gtp_encap_enable(gtp, data);
-	if (err < 0)
-		return err;
-
 	if (!data[IFLA_GTP_PDP_HASHSIZE]) {
 		hashsize = 1024;
 	} else {
@@ -677,12 +673,16 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	err = gtp_hashtable_new(gtp, hashsize);
 	if (err < 0)
-		goto out_encap;
+		return err;
+
+	err = gtp_encap_enable(gtp, data);
+	if (err < 0)
+		goto out_hashtable;
 
 	err = register_netdevice(dev);
 	if (err < 0) {
 		netdev_dbg(dev, "failed to register new netdev %d\n", err);
-		goto out_hashtable;
+		goto out_encap;
 	}
 
 	gn = net_generic(dev_net(dev), gtp_net_id);
@@ -693,11 +693,11 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
 
 	return 0;
 
+out_encap:
+	gtp_encap_disable(gtp);
 out_hashtable:
 	kfree(gtp->addr_hash);
 	kfree(gtp->tid_hash);
-out_encap:
-	gtp_encap_disable(gtp);
 	return err;
 }
 
-- 
2.24.3

Re: [PATCH v3 net] gtp: fix an use-before-init in gtp_newlink()

[Jakub Kicinski]

On Tue, 27 Oct 2020 20:48:46 +0900 Masahiro Fujiwara wrote:
> *_pdp_find() from gtp_encap_recv() would trigger a crash when a peer
> sends GTP packets while creating new GTP device.
> 
> RIP: 0010:gtp1_pdp_find.isra.0+0x68/0x90 [gtp]
> <SNIP>
> Call Trace:
>  <IRQ>
>  gtp_encap_recv+0xc2/0x2e0 [gtp]
>  ? gtp1_pdp_find.isra.0+0x90/0x90 [gtp]
>  udp_queue_rcv_one_skb+0x1fe/0x530
>  udp_queue_rcv_skb+0x40/0x1b0
>  udp_unicast_rcv_skb.isra.0+0x78/0x90
>  __udp4_lib_rcv+0x5af/0xc70
>  udp_rcv+0x1a/0x20
>  ip_protocol_deliver_rcu+0xc5/0x1b0
>  ip_local_deliver_finish+0x48/0x50
>  ip_local_deliver+0xe5/0xf0
>  ? ip_protocol_deliver_rcu+0x1b0/0x1b0
> 
> gtp_encap_enable() should be called after gtp_hastable_new() otherwise
> *_pdp_find() will access the uninitialized hash table.
> 
> Fixes: 1e3a3abd8b28 ("gtp: make GTP sockets in gtp_newlink optional")
> Signed-off-by: Masahiro Fujiwara <fujiwara.masahiro@gmail.com>

Applied, thank you!