syzbot


KMSAN: uninit-value in br_mdb_ip_get

Status: fixed on 2019/05/31 13:01
Reported-by: syzbot+8dfe5ee27aa6d2e396c2@syzkaller.appspotmail.com
Fix commit: 1515a63fc413 net: bridge: always clear mcast matching struct on reports and leaves
First crash: 1316d, last: 1240d

Sample crash report:
==================================================================
BUG: KMSAN: uninit-value in __rhashtable_lookup include/linux/rhashtable.h:505 [inline]
BUG: KMSAN: uninit-value in rhashtable_lookup include/linux/rhashtable.h:534 [inline]
BUG: KMSAN: uninit-value in br_mdb_ip_get+0x52b/0x740 net/bridge/br_multicast.c:99
CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 5.1.0-rc2+ #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x173/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:624
 __msan_warning+0x7a/0xf0 mm/kmsan/kmsan_instr.c:310
 __rhashtable_lookup include/linux/rhashtable.h:505 [inline]
 rhashtable_lookup include/linux/rhashtable.h:534 [inline]
 br_mdb_ip_get+0x52b/0x740 net/bridge/br_multicast.c:99
 br_multicast_new_group+0xa7/0x1640 net/bridge/br_multicast.c:469
 br_multicast_add_group+0x23f/0xf40 net/bridge/br_multicast.c:554
 br_ip4_multicast_add_group net/bridge/br_multicast.c:608 [inline]
 br_ip4_multicast_igmp3_report net/bridge/br_multicast.c:974 [inline]
 br_multicast_ipv4_rcv net/bridge/br_multicast.c:1631 [inline]
 br_multicast_rcv+0x5049/0x8030 net/bridge/br_multicast.c:1741
 br_handle_frame_finish+0x692/0x1bc0 net/bridge/br_input.c:108
 br_nf_hook_thresh net/bridge/br_netfilter_hooks.c:1005 [inline]
 br_nf_pre_routing_finish+0x188d/0x2500 net/bridge/br_netfilter_hooks.c:410
 NF_HOOK include/linux/netfilter.h:289 [inline]
 br_nf_pre_routing+0x1655/0x17a0 net/bridge/br_netfilter_hooks.c:506
 nf_hook_entry_hookfn include/linux/netfilter.h:119 [inline]
 nf_hook_slow+0x176/0x3d0 net/netfilter/core.c:511
 nf_hook include/linux/netfilter.h:244 [inline]
 NF_HOOK include/linux/netfilter.h:287 [inline]
 br_handle_frame+0xe4e/0x2020 net/bridge/br_input.c:305
 __netif_receive_skb_core+0x1edd/0x5030 net/core/dev.c:4902
 __netif_receive_skb_one_core net/core/dev.c:4971 [inline]
 __netif_receive_skb net/core/dev.c:5083 [inline]
 process_backlog+0x683/0x10e0 net/core/dev.c:5923
 napi_poll net/core/dev.c:6346 [inline]
 net_rx_action+0x78b/0x1a60 net/core/dev.c:6412
 __do_softirq+0x53f/0x93a kernel/softirq.c:294
 run_ksoftirqd+0x26/0x50 kernel/softirq.c:659
 smpboot_thread_fn+0x4d0/0x9f0 kernel/smpboot.c:164
 kthread+0x4a1/0x4e0 kernel/kthread.c:254
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355

Local variable description: ----br_group.i.i@br_multicast_rcv
Variable was created at:
 br_multicast_rcv+0x1f2/0x8030 net/bridge/br_multicast.c:1730
 br_handle_frame_finish+0x692/0x1bc0 net/bridge/br_input.c:108
==================================================================

Crashes (5):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kmsan-gce 2019/03/28 12:26 https://github.com/google/kmsan.git master 35def5ce9fa7 f94f56fe .config log report
ci-upstream-kmsan-gce 2019/01/11 16:14 https://github.com/google/kmsan.git master 02f2d5aea531 c3f3344c .config log report
ci-upstream-kmsan-gce 2019/01/11 14:12 https://github.com/google/kmsan.git master 02f2d5aea531 c3f3344c .config log report
ci-upstream-kmsan-gce 2019/01/11 08:59 https://github.com/google/kmsan.git master 02f2d5aea531 80dde172 .config log report
ci-upstream-kmsan-gce 2019/01/11 02:28 https://github.com/google/kmsan.git master 02f2d5aea531 80dde172 .config log report