Re: [PATCH net] caif: Fix crash due to uninitialized net name-space.

On Tue, Jan 24, 2012 at 5:27 PM, Sjur Brændeland
[off-list ref] wrote:

net_generic() calls BUG_ON() if called with uninitialized
network name-space. Add check if net is initialized before
calling net_generic(). This fixes the following oops:

[  200.752016] kernel BUG at include/net/netns/generic.h:40!
...
[  200.752016]  [<ffffffff825c3cea>] ? get_cfcnfg+0x3a/0x180
[  200.752016]  [<ffffffff821cf0b0>] ? lockdep_rtnl_is_held+0x10/0x20
[  200.752016]  [<ffffffff825c41be>] caif_device_notify+0x2e/0x530
[  200.752016]  [<ffffffff810d61b7>] notifier_call_chain+0x67/0x110
[  200.752016]  [<ffffffff810d67c1>] raw_notifier_call_chain+0x11/0x20
[  200.752016]  [<ffffffff821bae82>] call_netdevice_notifiers+0x32/0x60
[  200.752016]  [<ffffffff821c2b26>] register_netdevice+0x196/0x300
[  200.752016]  [<ffffffff821c2ca9>] register_netdev+0x19/0x30
[  200.752016]  [<ffffffff81c1c67a>] loopback_net_init+0x4a/0xa0
[  200.752016]  [<ffffffff821b5e62>] ops_init+0x42/0x180
[  200.752016]  [<ffffffff821b600b>] setup_net+0x6b/0x100
[  200.752016]  [<ffffffff821b6466>] copy_net_ns+0x86/0x110
[  200.752016]  [<ffffffff810d5789>] create_new_namespaces+0xd9/0x190

Signed-off-by: Sjur Brændeland <redacted>
---

Hi Sasha,

Do you have any chance to review and test this patch?
I'd like to get the net namespace handling this right this time ...

Thanks,
Sjur

Works for me.

Tested-by: Sasha Levin <redacted>

net_generic() calls BUG_ON() if called with uninitialized
network name-space. Add check if net is initialized before
calling net_generic(). This fixes the following oops:

[  200.752016] kernel BUG at include/net/netns/generic.h:40!
...
[  200.752016]  [<ffffffff825c3cea>] ? get_cfcnfg+0x3a/0x180
[  200.752016]  [<ffffffff821cf0b0>] ? lockdep_rtnl_is_held+0x10/0x20
[  200.752016]  [<ffffffff825c41be>] caif_device_notify+0x2e/0x530
[  200.752016]  [<ffffffff810d61b7>] notifier_call_chain+0x67/0x110
[  200.752016]  [<ffffffff810d67c1>] raw_notifier_call_chain+0x11/0x20
[  200.752016]  [<ffffffff821bae82>] call_netdevice_notifiers+0x32/0x60
[  200.752016]  [<ffffffff821c2b26>] register_netdevice+0x196/0x300
[  200.752016]  [<ffffffff821c2ca9>] register_netdev+0x19/0x30
[  200.752016]  [<ffffffff81c1c67a>] loopback_net_init+0x4a/0xa0
[  200.752016]  [<ffffffff821b5e62>] ops_init+0x42/0x180
[  200.752016]  [<ffffffff821b600b>] setup_net+0x6b/0x100
[  200.752016]  [<ffffffff821b6466>] copy_net_ns+0x86/0x110
[  200.752016]  [<ffffffff810d5789>] create_new_namespaces+0xd9/0x190

Signed-off-by: Sjur Brændeland <redacted>
Tested-by: Sasha Levin <redacted>

---

Hi Sasha and Dave,

[Sasha]

Works for me.

Thank you Sasha for reporting this bug and testing my patch,
I appreciate it.

[Dave]

Please post all networking patches CC:'d

Sorry, I missed the obvious.
I'm resending the same patch as yesterday, this time to:netdev
and with "Tested-by: Sasha". Please apply to net.

Thanks,
Sjur

 net/caif/caif_dev.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/net/caif/caif_dev.c b/net/caif/caif_dev.c
index 673728a..6110ade 100644
--- a/net/caif/caif_dev.c
+++ b/net/caif/caif_dev.c

@@ -371,6 +371,14 @@ static int caif_device_notify(struct notifier_block *me, unsigned long what,
 	struct cflayer *layer, *link_support;
 	int head_room = 0;
 	struct caif_device_entry_list *caifdevs;
+	int len;
+
+	rcu_read_lock();
+	len = rcu_dereference(dev_net(dev)->gen)->len;
+	rcu_read_unlock();
+
+	if (caif_net_id == 0 || caif_net_id > len)
+		return 0;
 
 	cfg = get_cfcnfg(dev_net(dev));
 	caifdevs = caif_device_list(dev_net(dev));

-- 
1.7.0.4

Le mercredi 25 janvier 2012 à 21:33 +0100, Sjur Brændeland a écrit :

This looks wrong.

This should not be needed, something is broken elsewhere.

Le mercredi 25 janvier 2012 à 21:33 +0100, Sjur Brændeland a écrit :

I believe the problem is in net_namespace infrastructure, not in CAIF.

Could you test following patch instead ?

[PATCH] netns: fix net_alloc_generic()

When a new net namespace is created, we should attach to it a "struct
net_generic" with enough slots (even empty), or we can hit the following
BUG_ON() :

[  200.752016] kernel BUG at include/net/netns/generic.h:40!
...
[  200.752016]  [<ffffffff825c3cea>] ? get_cfcnfg+0x3a/0x180
[  200.752016]  [<ffffffff821cf0b0>] ? lockdep_rtnl_is_held+0x10/0x20
[  200.752016]  [<ffffffff825c41be>] caif_device_notify+0x2e/0x530
[  200.752016]  [<ffffffff810d61b7>] notifier_call_chain+0x67/0x110
[  200.752016]  [<ffffffff810d67c1>] raw_notifier_call_chain+0x11/0x20
[  200.752016]  [<ffffffff821bae82>] call_netdevice_notifiers+0x32/0x60
[  200.752016]  [<ffffffff821c2b26>] register_netdevice+0x196/0x300
[  200.752016]  [<ffffffff821c2ca9>] register_netdev+0x19/0x30
[  200.752016]  [<ffffffff81c1c67a>] loopback_net_init+0x4a/0xa0
[  200.752016]  [<ffffffff821b5e62>] ops_init+0x42/0x180
[  200.752016]  [<ffffffff821b600b>] setup_net+0x6b/0x100
[  200.752016]  [<ffffffff821b6466>] copy_net_ns+0x86/0x110
[  200.752016]  [<ffffffff810d5789>] create_new_namespaces+0xd9/0x190

net_alloc_generic() should take into account the maximum index into the
ptr array, as a subsystem might use net_generic() anytime.

This also reduces number of reallocations in net_assign_generic()

Reported-by: Sasha Levin <redacted>
Signed-off-by: Eric Dumazet <redacted>
Cc: Sjur Brændeland <redacted>
Cc: Eric W. Biederman <redacted>
Cc: Pavel Emelyanov <redacted>
---
 net/core/net_namespace.c |   31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index aefcd7a..0e950fd 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c

@@ -30,6 +30,20 @@ EXPORT_SYMBOL(init_net);
 
 #define INITIAL_NET_GEN_PTRS	13 /* +1 for len +2 for rcu_head */
 
+static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;
+
+static struct net_generic *net_alloc_generic(void)
+{
+	struct net_generic *ng;
+	size_t generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);
+
+	ng = kzalloc(generic_size, GFP_KERNEL);
+	if (ng)
+		ng->len = max_gen_ptrs;
+
+	return ng;
+}
+
 static int net_assign_generic(struct net *net, int id, void *data)
 {
 	struct net_generic *ng, *old_ng;

@@ -43,8 +57,7 @@ static int net_assign_generic(struct net *net, int id, void *data)
 	if (old_ng->len >= id)
 		goto assign;
 
-	ng = kzalloc(sizeof(struct net_generic) +
-			id * sizeof(void *), GFP_KERNEL);
+	ng = net_alloc_generic();
 	if (ng == NULL)
 		return -ENOMEM;
 

@@ -59,7 +72,6 @@ static int net_assign_generic(struct net *net, int id, void *data)
 	 * the old copy for kfree after a grace period.
 	 */
 
-	ng->len = id;
 	memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*));
 
 	rcu_assign_pointer(net->gen, ng);

@@ -161,18 +173,6 @@ out_undo:
 	goto out;
 }
 
-static struct net_generic *net_alloc_generic(void)
-{
-	struct net_generic *ng;
-	size_t generic_size = sizeof(struct net_generic) +
-		INITIAL_NET_GEN_PTRS * sizeof(void *);
-
-	ng = kzalloc(generic_size, GFP_KERNEL);
-	if (ng)
-		ng->len = INITIAL_NET_GEN_PTRS;
-
-	return ng;
-}
 
 #ifdef CONFIG_NET_NS
 static struct kmem_cache *net_cachep;

@@ -483,6 +483,7 @@ again:
 			}
 			return error;
 		}
+		max_gen_ptrs = max_t(unsigned int, max_gen_ptrs, *ops->id);
 	}
 	error = __register_pernet_operations(list, ops);
 	if (error) {

I believe the problem is in net_namespace infrastructure, not in CAIF.

Could you test following patch instead ?

[PATCH] netns: fix net_alloc_generic()

When a new net namespace is created, we should attach to it a "struct
net_generic" with enough slots (even empty), or we can hit the following
BUG_ON() :

[  200.752016] kernel BUG at include/net/netns/generic.h:40!
...
[  200.752016]  [<ffffffff825c3cea>] ? get_cfcnfg+0x3a/0x180
[  200.752016]  [<ffffffff821cf0b0>] ? lockdep_rtnl_is_held+0x10/0x20
[  200.752016]  [<ffffffff825c41be>] caif_device_notify+0x2e/0x530
[  200.752016]  [<ffffffff810d61b7>] notifier_call_chain+0x67/0x110
[  200.752016]  [<ffffffff810d67c1>] raw_notifier_call_chain+0x11/0x20
[  200.752016]  [<ffffffff821bae82>] call_netdevice_notifiers+0x32/0x60
[  200.752016]  [<ffffffff821c2b26>] register_netdevice+0x196/0x300
[  200.752016]  [<ffffffff821c2ca9>] register_netdev+0x19/0x30
[  200.752016]  [<ffffffff81c1c67a>] loopback_net_init+0x4a/0xa0
[  200.752016]  [<ffffffff821b5e62>] ops_init+0x42/0x180
[  200.752016]  [<ffffffff821b600b>] setup_net+0x6b/0x100
[  200.752016]  [<ffffffff821b6466>] copy_net_ns+0x86/0x110
[  200.752016]  [<ffffffff810d5789>] create_new_namespaces+0xd9/0x190

net_alloc_generic() should take into account the maximum index into the
ptr array, as a subsystem might use net_generic() anytime.

I'm not sure I understand it correctly, but subsystem can only use the
net_generic() only (!) after the net_assign_generic() is performed.

Le jeudi 26 janvier 2012 à 14:44 +0400, Pavel Emelyanov a écrit :

quoted

I believe the problem is in net_namespace infrastructure, not in CAIF.

Could you test following patch instead ?

[PATCH] netns: fix net_alloc_generic()

When a new net namespace is created, we should attach to it a "struct
net_generic" with enough slots (even empty), or we can hit the following
BUG_ON() :

[  200.752016] kernel BUG at include/net/netns/generic.h:40!
...
[  200.752016]  [<ffffffff825c3cea>] ? get_cfcnfg+0x3a/0x180
[  200.752016]  [<ffffffff821cf0b0>] ? lockdep_rtnl_is_held+0x10/0x20
[  200.752016]  [<ffffffff825c41be>] caif_device_notify+0x2e/0x530
[  200.752016]  [<ffffffff810d61b7>] notifier_call_chain+0x67/0x110
[  200.752016]  [<ffffffff810d67c1>] raw_notifier_call_chain+0x11/0x20
[  200.752016]  [<ffffffff821bae82>] call_netdevice_notifiers+0x32/0x60
[  200.752016]  [<ffffffff821c2b26>] register_netdevice+0x196/0x300
[  200.752016]  [<ffffffff821c2ca9>] register_netdev+0x19/0x30
[  200.752016]  [<ffffffff81c1c67a>] loopback_net_init+0x4a/0xa0
[  200.752016]  [<ffffffff821b5e62>] ops_init+0x42/0x180
[  200.752016]  [<ffffffff821b600b>] setup_net+0x6b/0x100
[  200.752016]  [<ffffffff821b6466>] copy_net_ns+0x86/0x110
[  200.752016]  [<ffffffff810d5789>] create_new_namespaces+0xd9/0x190

net_alloc_generic() should take into account the maximum index into the
ptr array, as a subsystem might use net_generic() anytime.

I'm not sure I understand it correctly, but subsystem can only use the
net_generic() only (!) after the net_assign_generic() is performed.

Yes, but here, loopback_net_init() calls register_netdev()

So every subsystems _notify are called, even if subsystem _init_net()
was not yet called.

Its a chicken and egg problem.

On Thu, 2012-01-26 at 11:41 +0100, Eric Dumazet wrote:

Could you test following patch instead ?

Works for me.

-- 

Sasha.

From: Eric Dumazet <redacted>
Date: Thu, 26 Jan 2012 11:41:38 +0100

[PATCH] netns: fix net_alloc_generic()

When a new net namespace is created, we should attach to it a "struct
net_generic" with enough slots (even empty), or we can hit the following
BUG_ON() :

...

net_alloc_generic() should take into account the maximum index into the
ptr array, as a subsystem might use net_generic() anytime.

This also reduces number of reallocations in net_assign_generic()

Reported-by: Sasha Levin <redacted>
Signed-off-by: Eric Dumazet <redacted>

Applied and queued up for -stable, thanks.