user/sven/linux.git/net/tipc/socket.c, branch v4.9.53

tipc: Fix tipc_sk_reinit race conditions

2017-06-17T04:41:49Z

[ Upstream commit 9dbbfb0ab6680c6a85609041011484e6658e7d3c ] There are two problems with the function tipc_sk_reinit. Firstly it's doing a manual walk over an rhashtable. This is broken as an rhashtable can be resized and if you manually walk over it during a resize then you may miss entries. Secondly it's missing memory barriers as previously the code used spinlocks which provide the barriers implicitly. This patch fixes both problems. Fixes: 07f6c4bc048a ("tipc: convert tipc reference table to...") Signed-off-by: Herbert Xu Acked-by: Ying Xue Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

tipc: resolve connection flow control compatibility problem

2016-11-26T02:38:16Z

In commit 10724cc7bb78 ("tipc: redesign connection-level flow control") we replaced the previous message based flow control with one based on 1k blocks. In order to ensure backwards compatibility the mechanism falls back to using message as base unit when it senses that the peer doesn't support the new algorithm. The default flow control window, i.e., how many units can be sent before the sender blocks and waits for an acknowledge (aka advertisement) is 512. This was tested against the previous version, which uses an acknowledge frequency of on ack per 256 received message, and found to work fine. However, we missed the fact that versions older than Linux 3.15 use an acknowledge frequency of 512, which is exactly the limit where a 4.6+ sender will stop and wait for acknowledge. This would also work fine if it weren't for the fact that if the first sent message on a 4.6+ server side is an empty SYNACK, this one is also is counted as a sent message, while it is not counted as a received message on a legacy 3.15-receiver. This leads to the sender always being one step ahead of the receiver, a scenario causing the sender to block after 512 sent messages, while the receiver only has registered 511 read messages. Hence, the legacy receiver is not trigged to send an acknowledge, with a permanently blocked sender as result. We solve this deadlock by simply allowing the sender to send one more message before it blocks, i.e., by a making minimal change to the condition used for determining connection congestion. Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: eliminate obsolete socket locking policy description

2016-11-20T03:15:41Z

The comment block in socket.c describing the locking policy is obsolete, and does not reflect current reality. We remove it in this commit. Since the current locking policy is much simpler and follows a mainstream approach, we see no need to add a new description. Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: fix NULL pointer dereference in shutdown()

2016-08-15T20:55:36Z

tipc_msg_create() can return a NULL skb and if so, we shouldn't try to call tipc_node_xmit_skb() on it. general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 3 PID: 30298 Comm: trinity-c0 Not tainted 4.7.0-rc7+ #19 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 task: ffff8800baf09980 ti: ffff8800595b8000 task.ti: ffff8800595b8000 RIP: 0010:[] [] tipc_node_xmit_skb+0x6b/0x140 RSP: 0018:ffff8800595bfce8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000003023b0e0 RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffffffff83d12580 RBP: ffff8800595bfd78 R08: ffffed000b2b7f32 R09: 0000000000000000 R10: fffffbfff0759725 R11: 0000000000000000 R12: 1ffff1000b2b7f9f R13: ffff8800595bfd58 R14: ffffffff83d12580 R15: dffffc0000000000 FS: 00007fcdde242700(0000) GS:ffff88011af80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fcddde1db10 CR3: 000000006874b000 CR4: 00000000000006e0 DR0: 00007fcdde248000 DR1: 00007fcddd73d000 DR2: 00007fcdde248000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000090602 Stack: 0000000000000018 0000000000000018 0000000041b58ab3 ffffffff83954208 ffffffff830bb400 ffff8800595bfd30 ffffffff8309d767 0000000000000018 0000000000000018 ffff8800595bfd78 ffffffff8309da1a 00000000810ee611 Call Trace: [] tipc_shutdown+0x553/0x880 [] SyS_shutdown+0x14b/0x170 [] do_syscall_64+0x19c/0x410 [] entry_SYSCALL64_slow_path+0x25/0x25 Code: 90 00 b4 0b 83 c7 00 f1 f1 f1 f1 4c 8d 6d e0 c7 40 04 00 00 00 f4 c7 40 08 f3 f3 f3 f3 48 89 d8 48 c1 e8 03 c7 45 b4 00 00 00 00 <80> 3c 30 00 75 78 48 8d 7b 08 49 8d 75 c0 48 b8 00 00 00 00 00 RIP [] tipc_node_xmit_skb+0x6b/0x140 RSP ---[ end trace 57b0484e351e71f1 ]--- I feel like we should maybe return -ENOMEM or -ENOBUFS, but I'm not sure userspace is equipped to handle that. Anyway, this is better than a GPF and looks somewhat consistent with other tipc_msg_create() callers. Signed-off-by: Vegard Nossum Acked-by: Ying Xue Acked-by: Jon Maloy Signed-off-by: David S. Miller

tipc: fix socket timer deadlock

2016-06-18T04:38:10Z

We sometimes observe a 'deadly embrace' type deadlock occurring between mutually connected sockets on the same node. This happens when the one-hour peer supervision timers happen to expire simultaneously in both sockets. The scenario is as follows: CPU 1: CPU 2: -------- -------- tipc_sk_timeout(sk1) tipc_sk_timeout(sk2) lock(sk1.slock) lock(sk2.slock) msg_create(probe) msg_create(probe) unlock(sk1.slock) unlock(sk2.slock) tipc_node_xmit_skb() tipc_node_xmit_skb() tipc_node_xmit() tipc_node_xmit() tipc_sk_rcv(sk2) tipc_sk_rcv(sk1) lock(sk2.slock) lock((sk1.slock) filter_rcv() filter_rcv() tipc_sk_proto_rcv() tipc_sk_proto_rcv() msg_create(probe_rsp) msg_create(probe_rsp) tipc_sk_respond() tipc_sk_respond() tipc_node_xmit_skb() tipc_node_xmit_skb() tipc_node_xmit() tipc_node_xmit() tipc_sk_rcv(sk1) tipc_sk_rcv(sk2) lock((sk1.slock) lock((sk2.slock) ===> DEADLOCK ===> DEADLOCK Further analysis reveals that there are three different locations in the socket code where tipc_sk_respond() is called within the context of the socket lock, with ensuing risk of similar deadlocks. We now solve this by passing a buffer queue along with all upcalls where sk_lock.slock may potentially be held. Response or rejected message buffers are accumulated into this queue instead of being sent out directly, and only sent once we know we are safely outside the slock context. Reported-by: GUNA Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2016-05-18T00:05:30Z

Pull trivial tree updates from Jiri Kosina. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (21 commits) gitignore: fix wording mfd: ab8500-debugfs: fix "between" in printk memstick: trivial fix of spelling mistake on management cpupowerutils: bench: fix "average" treewide: Fix typos in printk IB/mlx4: printk fix pinctrl: sirf/atlas7: fix printk spelling serial: mctrl_gpio: Grammar s/lines GPIOs/line GPIOs/, /sets/set/ w1: comment spelling s/minmum/minimum/ Blackfin: comment spelling s/divsor/divisor/ metag: Fix misspellings in comments. ia64: Fix misspellings in comments. hexagon: Fix misspellings in comments. tools/perf: Fix misspellings in comments. cris: Fix misspellings in comments. c6x: Fix misspellings in comments. blackfin: Fix misspelling of 'register' in comment. avr32: Fix misspelling of 'definitions' in comment. treewide: Fix typos in printk Doc: treewide : Fix typos in DocBook/filesystem.xml ...

tipc: check nl sock before parsing nested attributes

2016-05-17T01:58:54Z

Make sure the socket for which the user is listing publication exists before parsing the socket netlink attributes. Prior to this patch a call without any socket caused a NULL pointer dereference in tipc_nl_publ_dump(). Tested-and-reported-by: Baozeng Ding Signed-off-by: Richard Alpe Acked-by: Jon Maloy Signed-off-by: David S. Miller

tipc: redesign connection-level flow control

2016-05-03T19:51:16Z

There are two flow control mechanisms in TIPC; one at link level that handles network congestion, burst control, and retransmission, and one at connection level which' only remaining task is to prevent overflow in the receiving socket buffer. In TIPC, the latter task has to be solved end-to-end because messages can not be thrown away once they have been accepted and delivered upwards from the link layer, i.e, we can never permit the receive buffer to overflow. Currently, this algorithm is message based. A counter in the receiving socket keeps track of number of consumed messages, and sends a dedicated acknowledge message back to the sender for each 256 consumed message. A counter at the sending end keeps track of the sent, not yet acknowledged messages, and blocks the sender if this number ever reaches 512 unacknowledged messages. When the missing acknowledge arrives, the socket is then woken up for renewed transmission. This works well for keeping the message flow running, as it almost never happens that a sender socket is blocked this way. A problem with the current mechanism is that it potentially is very memory consuming. Since we don't distinguish between small and large messages, we have to dimension the socket receive buffer according to a worst-case of both. I.e., the window size must be chosen large enough to sustain a reasonable throughput even for the smallest messages, while we must still consider a scenario where all messages are of maximum size. Hence, the current fix window size of 512 messages and a maximum message size of 66k results in a receive buffer of 66 MB when truesize(66k) = 131k is taken into account. It is possible to do much better. This commit introduces an algorithm where we instead use 1024-byte blocks as base unit. This unit, always rounded upwards from the actual message size, is used when we advertise windows as well as when we count and acknowledge transmitted data. The advertised window is based on the configured receive buffer size in such a way that even the worst-case truesize/msgsize ratio always is covered. Since the smallest possible message size (from a flow control viewpoint) now is 1024 bytes, we can safely assume this ratio to be less than four, which is the value we are now using. This way, we have been able to reduce the default receive buffer size from 66 MB to 2 MB with maintained performance. In order to keep this solution backwards compatible, we introduce a new capability bit in the discovery protocol, and use this throughout the message sending/reception path to always select the right unit. Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: propagate peer node capabilities to socket layer

2016-05-03T19:51:15Z

During neighbor discovery, nodes advertise their capabilities as a bit map in a dedicated 16-bit field in the discovery message header. This bit map has so far only be stored in the node structure on the peer nodes, but we now see the need to keep a copy even in the socket structure. This commit adds this functionality. Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller

tipc: re-enable compensation for socket receive buffer double counting

2016-05-03T19:51:14Z

In the refactoring commit d570d86497ee ("tipc: enqueue arrived buffers in socket in separate function") we did by accident replace the test if (sk->sk_backlog.len == 0) atomic_set(&tsk->dupl_rcvcnt, 0); with if (sk->sk_backlog.len) atomic_set(&tsk->dupl_rcvcnt, 0); This effectively disables the compensation we have for the double receive buffer accounting that occurs temporarily when buffers are moved from the backlog to the socket receive queue. Until now, this has gone unnoticed because of the large receive buffer limits we are applying, but becomes indispensable when we reduce this buffer limit later in this series. We now fix this by inverting the mentioned condition. Acked-by: Ying Xue Signed-off-by: Jon Maloy Signed-off-by: David S. Miller