de514e0609
[ Upstream commit c7799c067c2ae33e348508c8afec354f3257ff25 ] Remove the second tipc_rcv() call in tipc_udp_recv(). We have just checked that the bearer is not up, and calling tipc_rcv() with a bearer that is not up leads to a TIPC div-by-zero crash in tipc_node_calculate_timer(). The crash is rare in practice, but can happen like this: We're enabling a bearer, but it's not yet up and fully initialized. At the same time we receive a discovery packet, and in tipc_udp_recv() we end up calling tipc_rcv() with the not-yet-initialized bearer, causing later the div-by-zero crash in tipc_node_calculate_timer(). Jon Maloy explains the impact of removing the second tipc_rcv() call: "link setup in the worst case will be delayed until the next arriving discovery messages, 1 sec later, and this is an acceptable delay." As the tipc_rcv() call is removed, just leave the function via the rcu_out label, so that we will kfree_skb(). [ 12.590450] Own node address <1.1.1>, network identity 1 [ 12.668088] divide error: 0000 [#1] SMP [ 12.676952] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.14.2-dirty #1 [ 12.679225] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-2.fc27 04/01/2014 [ 12.682095] task: ffff8c2a761edb80 task.stack: ffffa41cc0cac000 [ 12.684087] RIP: 0010:tipc_node_calculate_timer.isra.12+0x45/0x60 [tipc] [ 12.686486] RSP: 0018:ffff8c2a7fc838a0 EFLAGS: 00010246 [ 12.688451] RAX: 0000000000000000 RBX: ffff8c2a5b382600 RCX: 0000000000000000 [ 12.691197] RDX: 0000000000000000 RSI: ffff8c2a5b382600 RDI: ffff8c2a5b382600 [ 12.693945] RBP: ffff8c2a7fc838b0 R08: 0000000000000001 R09: 0000000000000001 [ 12.696632] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8c2a5d8949d8 [ 12.699491] R13: ffffffff95ede400 R14: 0000000000000000 R15: ffff8c2a5d894800 [ 12.702338] FS: 0000000000000000(0000) GS:ffff8c2a7fc80000(0000) knlGS:0000000000000000 [ 12.705099] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 12.706776] CR2: 0000000001bb9440 CR3: 00000000bd009001 CR4: 00000000003606e0 [ 12.708847] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 12.711016] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 12.712627] Call Trace: [ 12.713390] <IRQ> [ 12.714011] tipc_node_check_dest+0x2e8/0x350 [tipc] [ 12.715286] tipc_disc_rcv+0x14d/0x1d0 [tipc] [ 12.716370] tipc_rcv+0x8b0/0xd40 [tipc] [ 12.717396] ? minmax_running_min+0x2f/0x60 [ 12.718248] ? dst_alloc+0x4c/0xa0 [ 12.718964] ? tcp_ack+0xaf1/0x10b0 [ 12.719658] ? tipc_udp_is_known_peer+0xa0/0xa0 [tipc] [ 12.720634] tipc_udp_recv+0x71/0x1d0 [tipc] [ 12.721459] ? dst_alloc+0x4c/0xa0 [ 12.722130] udp_queue_rcv_skb+0x264/0x490 [ 12.722924] __udp4_lib_rcv+0x21e/0x990 [ 12.723670] ? ip_route_input_rcu+0x2dd/0xbf0 [ 12.724442] ? tcp_v4_rcv+0x958/0xa40 [ 12.725039] udp_rcv+0x1a/0x20 [ 12.725587] ip_local_deliver_finish+0x97/0x1d0 [ 12.726323] ip_local_deliver+0xaf/0xc0 [ 12.726959] ? ip_route_input_noref+0x19/0x20 [ 12.727689] ip_rcv_finish+0xdd/0x3b0 [ 12.728307] ip_rcv+0x2ac/0x360 [ 12.728839] __netif_receive_skb_core+0x6fb/0xa90 [ 12.729580] ? udp4_gro_receive+0x1a7/0x2c0 [ 12.730274] __netif_receive_skb+0x1d/0x60 [ 12.730953] ? __netif_receive_skb+0x1d/0x60 [ 12.731637] netif_receive_skb_internal+0x37/0xd0 [ 12.732371] napi_gro_receive+0xc7/0xf0 [ 12.732920] receive_buf+0x3c3/0xd40 [ 12.733441] virtnet_poll+0xb1/0x250 [ 12.733944] net_rx_action+0x23e/0x370 [ 12.734476] __do_softirq+0xc5/0x2f8 [ 12.734922] irq_exit+0xfa/0x100 [ 12.735315] do_IRQ+0x4f/0xd0 [ 12.735680] common_interrupt+0xa2/0xa2 [ 12.736126] </IRQ> [ 12.736416] RIP: 0010:native_safe_halt+0x6/0x10 [ 12.736925] RSP: 0018:ffffa41cc0cafe90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff4d [ 12.737756] RAX: 0000000000000000 RBX: ffff8c2a761edb80 RCX: 0000000000000000 [ 12.738504] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 12.739258] RBP: ffffa41cc0cafe90 R08: 0000014b5b9795e5 R09: ffffa41cc12c7e88 [ 12.740118] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 [ 12.740964] R13: ffff8c2a761edb80 R14: 0000000000000000 R15: 0000000000000000 [ 12.741831] default_idle+0x2a/0x100 [ 12.742323] arch_cpu_idle+0xf/0x20 [ 12.742796] default_idle_call+0x28/0x40 [ 12.743312] do_idle+0x179/0x1f0 [ 12.743761] cpu_startup_entry+0x1d/0x20 [ 12.744291] start_secondary+0x112/0x120 [ 12.744816] secondary_startup_64+0xa5/0xa5 [ 12.745367] Code: b9 f4 01 00 00 48 89 c2 48 c1 ea 02 48 3d d3 07 00 00 48 0f 47 d1 49 8b 0c 24 48 39 d1 76 07 49 89 14 24 48 89 d1 31 d2 48 89 df <48> f7 f1 89 c6 e8 81 6e ff ff 5b 41 5c 5d c3 66 90 66 2e 0f 1f [ 12.747527] RIP: tipc_node_calculate_timer.isra.12+0x45/0x60 [tipc] RSP: ffff8c2a7fc838a0 [ 12.748555] ---[ end trace 1399ab83390650fd ]--- [ 12.749296] Kernel panic - not syncing: Fatal exception in interrupt [ 12.750123] Kernel Offset: 0x13200000 from 0xffffffff82000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 12.751215] Rebooting in 60 seconds.. Fixes: c9b64d492b1f ("tipc: add replicast peer discovery") Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com> Cc: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.