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

From: Sjur BrÃndeland
Date: Wed Jan 25 2012 - 15:34:08 EST


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));
--
1.7.0.4

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