[PATCH] netns: fix net_alloc_generic()
From: Eric Dumazet
Date: Thu Jan 26 2012 - 05:41:41 EST
Le mercredi 25 janvier 2012 Ã 21:33 +0100, Sjur BrÃndeland a Ãcrit :
> 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 BrÃndeland <sjur.brandeland@xxxxxxxxxxxxxx>
> Tested-by: Sasha Levin <levinsasha928@xxxxxxxxx>
>
> ---
>
> 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));
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 <levinsasha928@xxxxxxxxx>
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Cc: Sjur BrÃndeland <sjur.brandeland@xxxxxxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
---
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) {
--
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