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authorGuillaume Nault <g.nault@alphalink.fr>2015-09-24 12:54:01 +0200
committerDavid S. Miller <davem@davemloft.net>2015-09-25 12:38:11 -0700
commit58a89ecaca53736aa465170530acea4f8be34ab4 (patch)
tree12a5ab0b549fe0b67e51f08429da56f6c8befd41 /drivers
parentnet: via/Kconfig: GENERIC_PCI_IOMAP required if PCI not selected (diff)
downloadlinux-dev-58a89ecaca53736aa465170530acea4f8be34ab4.tar.xz
linux-dev-58a89ecaca53736aa465170530acea4f8be34ab4.zip
ppp: fix lockdep splat in ppp_dev_uninit()
ppp_dev_uninit() locks all_ppp_mutex while under rtnl mutex protection. ppp_create_interface() must then lock these mutexes in that same order to avoid possible deadlock. [ 120.880011] ====================================================== [ 120.880011] [ INFO: possible circular locking dependency detected ] [ 120.880011] 4.2.0 #1 Not tainted [ 120.880011] ------------------------------------------------------- [ 120.880011] ppp-apitest/15827 is trying to acquire lock: [ 120.880011] (&pn->all_ppp_mutex){+.+.+.}, at: [<ffffffffa0145f56>] ppp_dev_uninit+0x64/0xb0 [ppp_generic] [ 120.880011] [ 120.880011] but task is already holding lock: [ 120.880011] (rtnl_mutex){+.+.+.}, at: [<ffffffff812e4255>] rtnl_lock+0x12/0x14 [ 120.880011] [ 120.880011] which lock already depends on the new lock. [ 120.880011] [ 120.880011] [ 120.880011] the existing dependency chain (in reverse order) is: [ 120.880011] [ 120.880011] -> #1 (rtnl_mutex){+.+.+.}: [ 120.880011] [<ffffffff81073a6f>] lock_acquire+0xcf/0x10e [ 120.880011] [<ffffffff813ab18a>] mutex_lock_nested+0x56/0x341 [ 120.880011] [<ffffffff812e4255>] rtnl_lock+0x12/0x14 [ 120.880011] [<ffffffff812d9d94>] register_netdev+0x11/0x27 [ 120.880011] [<ffffffffa0147b17>] ppp_ioctl+0x289/0xc98 [ppp_generic] [ 120.880011] [<ffffffff8113b367>] do_vfs_ioctl+0x4ea/0x532 [ 120.880011] [<ffffffff8113b3fd>] SyS_ioctl+0x4e/0x7d [ 120.880011] [<ffffffff813ad7d7>] entry_SYSCALL_64_fastpath+0x12/0x6f [ 120.880011] [ 120.880011] -> #0 (&pn->all_ppp_mutex){+.+.+.}: [ 120.880011] [<ffffffff8107334e>] __lock_acquire+0xb07/0xe76 [ 120.880011] [<ffffffff81073a6f>] lock_acquire+0xcf/0x10e [ 120.880011] [<ffffffff813ab18a>] mutex_lock_nested+0x56/0x341 [ 120.880011] [<ffffffffa0145f56>] ppp_dev_uninit+0x64/0xb0 [ppp_generic] [ 120.880011] [<ffffffff812d5263>] rollback_registered_many+0x19e/0x252 [ 120.880011] [<ffffffff812d5381>] rollback_registered+0x29/0x38 [ 120.880011] [<ffffffff812d53fa>] unregister_netdevice_queue+0x6a/0x77 [ 120.880011] [<ffffffffa0146a94>] ppp_release+0x42/0x79 [ppp_generic] [ 120.880011] [<ffffffff8112d9f6>] __fput+0xec/0x192 [ 120.880011] [<ffffffff8112dacc>] ____fput+0x9/0xb [ 120.880011] [<ffffffff8105447a>] task_work_run+0x66/0x80 [ 120.880011] [<ffffffff81001801>] prepare_exit_to_usermode+0x8c/0xa7 [ 120.880011] [<ffffffff81001900>] syscall_return_slowpath+0xe4/0x104 [ 120.880011] [<ffffffff813ad931>] int_ret_from_sys_call+0x25/0x9f [ 120.880011] [ 120.880011] other info that might help us debug this: [ 120.880011] [ 120.880011] Possible unsafe locking scenario: [ 120.880011] [ 120.880011] CPU0 CPU1 [ 120.880011] ---- ---- [ 120.880011] lock(rtnl_mutex); [ 120.880011] lock(&pn->all_ppp_mutex); [ 120.880011] lock(rtnl_mutex); [ 120.880011] lock(&pn->all_ppp_mutex); [ 120.880011] [ 120.880011] *** DEADLOCK *** Fixes: 8cb775bc0a34 ("ppp: fix device unregistration upon netns deletion") Reported-by: Sedat Dilek <sedat.dilek@gmail.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/ppp/ppp_generic.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 0481daf9201a..ed00446759b2 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -2755,6 +2755,7 @@ static struct ppp *ppp_create_interface(struct net *net, int unit,
*/
dev_net_set(dev, net);
+ rtnl_lock();
mutex_lock(&pn->all_ppp_mutex);
if (unit < 0) {
@@ -2785,7 +2786,7 @@ static struct ppp *ppp_create_interface(struct net *net, int unit,
ppp->file.index = unit;
sprintf(dev->name, "ppp%d", unit);
- ret = register_netdev(dev);
+ ret = register_netdevice(dev);
if (ret != 0) {
unit_put(&pn->units_idr, unit);
netdev_err(ppp->dev, "PPP: couldn't register device %s (%d)\n",
@@ -2797,6 +2798,7 @@ static struct ppp *ppp_create_interface(struct net *net, int unit,
atomic_inc(&ppp_unit_count);
mutex_unlock(&pn->all_ppp_mutex);
+ rtnl_unlock();
*retp = 0;
return ppp;