talos-obmc-linux/drivers/net/ppp, branch dev-4.13

ppp: fix race in ppp device destruction

2017-11-18T10:30:35+00:00

[ Upstream commit 6151b8b37b119e8e3a8401b080d532520c95faf4 ] ppp_release() tries to ensure that netdevices are unregistered before decrementing the unit refcount and running ppp_destroy_interface(). This is all fine as long as the the device is unregistered by ppp_release(): the unregister_netdevice() call, followed by rtnl_unlock(), guarantee that the unregistration process completes before rtnl_unlock() returns. However, the device may be unregistered by other means (like ppp_nl_dellink()). If this happens right before ppp_release() calling rtnl_lock(), then ppp_release() has to wait for the concurrent unregistration code to release the lock. But rtnl_unlock() releases the lock before completing the device unregistration process. This allows ppp_release() to proceed and eventually call ppp_destroy_interface() before the unregistration process completes. Calling free_netdev() on this partially unregistered device will BUG(): ------------[ cut here ]------------ kernel BUG at net/core/dev.c:8141! invalid opcode: 0000 [#1] SMP CPU: 1 PID: 1557 Comm: pppd Not tainted 4.14.0-rc2+ #4 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc26 04/01/2014 Call Trace: ppp_destroy_interface+0xd8/0xe0 [ppp_generic] ppp_disconnect_channel+0xda/0x110 [ppp_generic] ppp_unregister_channel+0x5e/0x110 [ppp_generic] pppox_unbind_sock+0x23/0x30 [pppox] pppoe_connect+0x130/0x440 [pppoe] SYSC_connect+0x98/0x110 ? do_fcntl+0x2c0/0x5d0 SyS_connect+0xe/0x10 entry_SYSCALL_64_fastpath+0x1a/0xa5 RIP: free_netdev+0x107/0x110 RSP: ffffc28a40573d88 ---[ end trace ed294ff0cc40eeff ]--- We could set the ->needs_free_netdev flag on PPP devices and move the ppp_destroy_interface() logic in the ->priv_destructor() callback. But that'd be quite intrusive as we'd first need to unlink from the other channels and units that depend on the device (the ones that used the PPPIOCCONNECT and PPPIOCATTACH ioctls). Instead, we can just let the netdevice hold a reference on its ppp_file. This reference is dropped in ->priv_destructor(), at the very end of the unregistration process, so that neither ppp_release() nor ppp_disconnect_channel() can call ppp_destroy_interface() in the interim. Reported-by: Beniamino Galvani Fixes: 8cb775bc0a34 ("ppp: fix device unregistration upon netns deletion") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

ppp: fix xmit recursion detection on ppp channels

2017-08-09T04:06:11+00:00

Commit e5dadc65f9e0 ("ppp: Fix false xmit recursion detect with two ppp devices") dropped the xmit_recursion counter incrementation in ppp_channel_push() and relied on ppp_xmit_process() for this task. But __ppp_channel_push() can also send packets directly (using the .start_xmit() channel callback), in which case the xmit_recursion counter isn't incremented anymore. If such packets get routed back to the parent ppp unit, ppp_xmit_process() won't notice the recursion and will call ppp_channel_push() on the same channel, effectively creating the deadlock situation that the xmit_recursion mechanism was supposed to prevent. This patch re-introduces the xmit_recursion counter incrementation in ppp_channel_push(). Since the xmit_recursion variable is now part of the parent ppp unit, incrementation is skipped if the channel doesn't have any. This is fine because only packets routed through the parent unit may enter the channel recursively. Finally, we have to ensure that pch->ppp is not going to be modified while executing ppp_channel_push(). Instead of taking this lock only while calling ppp_xmit_process(), we now have to hold it for the full ppp_channel_push() execution. This respects the ppp locks ordering which requires locking ->upl before ->downl. Fixes: e5dadc65f9e0 ("ppp: Fix false xmit recursion detect with two ppp devices") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller

ppp: Fix a scheduling-while-atomic bug in del_chan

2017-08-01T04:59:01+00:00

The PPTP set the pptp_sock_destruct as the sock's sk_destruct, it would trigger this bug when __sk_free is invoked in atomic context, because of the call path pptp_sock_destruct->del_chan->synchronize_rcu. Now move the synchronize_rcu to pptp_release from del_chan. This is the only one case which would free the sock and need the synchronize_rcu. The following is the panic I met with kernel 3.3.8, but this issue should exist in current kernel too according to the codes. BUG: scheduling while atomic __schedule_bug+0x5e/0x64 __schedule+0x55/0x580 ? ppp_unregister_channel+0x1cd5/0x1de0 [ppp_generic] ? dev_hard_start_xmit+0x423/0x530 ? sch_direct_xmit+0x73/0x170 __cond_resched+0x16/0x30 _cond_resched+0x22/0x30 wait_for_common+0x18/0x110 ? call_rcu_bh+0x10/0x10 wait_for_completion+0x12/0x20 wait_rcu_gp+0x34/0x40 ? wait_rcu_gp+0x40/0x40 synchronize_sched+0x1e/0x20 0xf8417298 0xf8417484 ? sock_queue_rcv_skb+0x109/0x130 __sk_free+0x16/0x110 ? udp_queue_rcv_skb+0x1f2/0x290 sk_free+0x16/0x20 __udp4_lib_rcv+0x3b8/0x650 Signed-off-by: Gao Feng Signed-off-by: David S. Miller

ppp: Fix false xmit recursion detect with two ppp devices

2017-07-18T18:20:33+00:00

The global percpu variable ppp_xmit_recursion is used to detect the ppp xmit recursion to avoid the deadlock, which is caused by one CPU tries to lock the xmit lock twice. But it would report false recursion when one CPU wants to send the skb from two different PPP devices, like one L2TP on the PPPoE. It is a normal case actually. Now use one percpu member of struct ppp instead of the gloable variable to detect the xmit recursion of one ppp device. Fixes: 55454a565836 ("ppp: avoid dealock on recursive xmit") Signed-off-by: Gao Feng Signed-off-by: Liu Jianying Signed-off-by: David S. Miller

net: add netlink_ext_ack argument to rtnl_link_ops.validate

2017-06-27T03:13:22+00:00

Add support for extended error reporting. Signed-off-by: Matthias Schiffer Acked-by: David Ahern Signed-off-by: David S. Miller

net: add netlink_ext_ack argument to rtnl_link_ops.newlink

2017-06-27T03:13:21+00:00

Add support for extended error reporting. Signed-off-by: Matthias Schiffer Acked-by: David Ahern Signed-off-by: David S. Miller

net: manual clean code which call skb_put_[data:zero]

2017-06-20T17:30:15+00:00

Signed-off-by: yuan linyu Signed-off-by: David S. Miller

pptp: Remove unused variable in pptp_release()

2017-06-19T03:53:56+00:00

Variable opt in pptp_release() is set but never used, thus needs to be removed. Signed-off-by: Christos Gkekas Signed-off-by: David S. Miller

networking: make skb_push & __skb_push return void pointers

2017-06-16T15:48:40+00:00

It seems like a historic accident that these return unsigned char *, and in many places that means casts are required, more often than not. Make these functions return void * and remove all the casts across the tree, adding a (u8 *) cast only where the unsigned char pointer was used directly, all done with the following spatch: @@ expression SKB, LEN; typedef u8; identifier fn = { skb_push, __skb_push, skb_push_rcsum }; @@ - *(fn(SKB, LEN)) + *(u8 *)fn(SKB, LEN) @@ expression E, SKB, LEN; identifier fn = { skb_push, __skb_push, skb_push_rcsum }; type T; @@ - E = ((T *)(fn(SKB, LEN))) + E = fn(SKB, LEN) @@ expression SKB, LEN; identifier fn = { skb_push, __skb_push, skb_push_rcsum }; @@ - fn(SKB, LEN)[0] + *(u8 *)fn(SKB, LEN) Note that the last part there converts from push(...)[0] to the more idiomatic *(u8 *)push(...). Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

networking: make skb_put & friends return void pointers

2017-06-16T15:48:39+00:00

It seems like a historic accident that these return unsigned char *, and in many places that means casts are required, more often than not. Make these functions (skb_put, __skb_put and pskb_put) return void * and remove all the casts across the tree, adding a (u8 *) cast only where the unsigned char pointer was used directly, all done with the following spatch: @@ expression SKB, LEN; typedef u8; identifier fn = { skb_put, __skb_put }; @@ - *(fn(SKB, LEN)) + *(u8 *)fn(SKB, LEN) @@ expression E, SKB, LEN; identifier fn = { skb_put, __skb_put }; type T; @@ - E = ((T *)(fn(SKB, LEN))) + E = fn(SKB, LEN) which actually doesn't cover pskb_put since there are only three users overall. A handful of stragglers were converted manually, notably a macro in drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many instances in net/bluetooth/hci_sock.c. In the former file, I also had to fix one whitespace problem spatch introduced. Signed-off-by: Johannes Berg Signed-off-by: David S. Miller