================================================================== BUG: KMSAN: uninit-value in memcmp+0x11d/0x180 lib/string.c:863 CPU: 0 PID: 5708 Comm: syz-executor478 Not tainted 4.19.0-rc4+ #61 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+0x2f6/0x430 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:917 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:500 memcmp+0x11d/0x180 lib/string.c:863 __hw_addr_del_ex net/core/dev_addr_lists.c:123 [inline] __dev_mc_del+0x169/0x6c0 net/core/dev_addr_lists.c:710 dev_mc_del+0x6d/0x80 net/core/dev_addr_lists.c:728 igmp6_group_dropped+0x2c5/0x12e0 net/ipv6/mcast.c:712 __ipv6_dev_mc_dec+0x6f1/0xbb0 net/ipv6/mcast.c:960 addrconf_leave_solict net/ipv6/addrconf.c:2110 [inline] __ipv6_ifa_notify+0x9c4/0x17c0 net/ipv6/addrconf.c:5696 addrconf_ifdown+0x1813/0x2670 net/ipv6/addrconf.c:3762 addrconf_notify+0x2c2/0x5d50 net/ipv6/addrconf.c:3573 notifier_call_chain kernel/notifier.c:93 [inline] __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x13e/0x240 kernel/notifier.c:401 call_netdevice_notifiers_info net/core/dev.c:1733 [inline] call_netdevice_notifiers net/core/dev.c:1751 [inline] dev_close_many+0x627/0x9e0 net/core/dev.c:1503 rollback_registered_many+0x9eb/0x2040 net/core/dev.c:7929 rollback_registered net/core/dev.c:7994 [inline] unregister_netdevice_queue+0x547/0xa40 net/core/dev.c:9038 unregister_netdevice include/linux/netdevice.h:2589 [inline] __tun_detach+0x220c/0x2c70 drivers/net/tun.c:729 tun_detach drivers/net/tun.c:746 [inline] tun_chr_close+0xda/0x1c0 drivers/net/tun.c:3272 __fput+0x4ee/0xe50 fs/file_table.c:278 ____fput+0x37/0x40 fs/file_table.c:309 task_work_run+0x457/0x4d0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop arch/x86/entry/common.c:166 [inline] prepare_exit_to_usermode+0x33e/0x410 arch/x86/entry/common.c:197 syscall_return_slowpath+0xf3/0x790 arch/x86/entry/common.c:268 do_syscall_64+0xde/0x100 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x63/0xe7 RIP: 0033:0x400ff0 Code: 01 f0 ff ff 0f 83 b0 0a 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d dd 16 2d 00 00 75 14 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 84 0a 00 00 c3 48 83 ec 08 e8 3a 01 00 00 RSP: 002b:00007ffc4982ac38 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000400ff0 RDX: 00000000200000c0 RSI: 0000000000008914 RDI: 0000000000000005 RBP: 00000000000169d1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000401f90 R14: 0000000000000000 R15: 0000000000000000 Local variable description: ----buf@igmp6_group_dropped Variable was created at: igmp6_group_dropped+0x49/0x12e0 net/ipv6/mcast.c:700 __ipv6_dev_mc_dec+0x6f1/0xbb0 net/ipv6/mcast.c:960 ==================================================================