bisecting fixing commit since 3f2ecb86cb909da0b9157fd2952ad79924cbe5ae building syzkaller on 04201c0669446145fd9c347c5538da0ca13ff29b testing commit 3f2ecb86cb909da0b9157fd2952ad79924cbe5ae with gcc (GCC) 8.4.1 20210217 kernel signature: 45fde5422fa264d5747fee7966d049e568554b81e4fe8eecc58f5dac76828315 run #0: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #1: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #2: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #3: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #4: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #5: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #6: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #7: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #8: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #9: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #10: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #11: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #12: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #13: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #14: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #15: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #16: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #17: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #18: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #19: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit testing current HEAD cf256fbcbe347b7d0ff58fe2dfa382a156bd3694 testing commit cf256fbcbe347b7d0ff58fe2dfa382a156bd3694 with gcc (GCC) 8.4.1 20210217 kernel signature: e4004c0836b5290f936367db84c91cd1c93e5ecd5c1fbd9eb277b55ffb3425d1 run #0: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #1: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #2: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #3: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #4: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #5: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #6: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #7: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #8: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #9: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit revisions tested: 2, total time: 28m2.375216744s (build: 21m13.162521352s, test: 6m7.874117877s) the crash still happens on HEAD commit msg: Linux 4.14.231 crash: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit IPv6: ADDRCONF(NETDEV_CHANGE): veth0_vlan: link becomes ready device veth0_vlan entered promiscuous mode IPv6: ADDRCONF(NETDEV_CHANGE): vlan0: link becomes ready ================================================================== IPv6: ADDRCONF(NETDEV_CHANGE): vlan1: link becomes ready BUG: KASAN: slab-out-of-bounds in ether_addr_equal include/linux/etherdevice.h:321 [inline] BUG: KASAN: slab-out-of-bounds in ipvlan_xmit_mode_l2 drivers/net/ipvlan/ipvlan_core.c:542 [inline] BUG: KASAN: slab-out-of-bounds in ipvlan_queue_xmit+0xfe2/0x11e0 drivers/net/ipvlan/ipvlan_core.c:583 device veth1_vlan entered promiscuous mode Read of size 4 at addr ffff88809c2e3abf by task syz-executor.2/9704 IPv6: ADDRCONF(NETDEV_UP): macvlan0: link is not ready CPU: 0 PID: 9704 Comm: syz-executor.2 Not tainted 4.14.231-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x14b/0x1e7 lib/dump_stack.c:58 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252 IPv6: ADDRCONF(NETDEV_UP): macvlan1: link is not ready kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold.7+0x11a/0x2d3 mm/kasan/report.c:393 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 ether_addr_equal include/linux/etherdevice.h:321 [inline] ipvlan_xmit_mode_l2 drivers/net/ipvlan/ipvlan_core.c:542 [inline] ipvlan_queue_xmit+0xfe2/0x11e0 drivers/net/ipvlan/ipvlan_core.c:583 IPv6: ADDRCONF(NETDEV_UP): veth0_macvtap: link is not ready ipvlan_start_xmit+0x4a/0x150 drivers/net/ipvlan/ipvlan_main.c:286 __netdev_start_xmit include/linux/netdevice.h:4051 [inline] netdev_start_xmit include/linux/netdevice.h:4060 [inline] packet_direct_xmit+0x3ed/0x630 net/packet/af_packet.c:269 packet_snd.isra.30+0x9ad/0x2aa0 net/packet/af_packet.c:3024 IPv6: ADDRCONF(NETDEV_UP): veth1_macvtap: link is not ready device veth0_macvtap entered promiscuous mode IPv6: ADDRCONF(NETDEV_UP): macvtap0: link is not ready device veth1_macvtap entered promiscuous mode IPv6: ADDRCONF(NETDEV_UP): macsec0: link is not ready IPv6: ADDRCONF(NETDEV_UP): veth0_to_batadv: link is not ready packet_sendmsg+0x10c9/0x2da0 net/packet/af_packet.c:3049 IPv6: ADDRCONF(NETDEV_UP): veth1_to_batadv: link is not ready batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:656 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 sock_write_iter+0x20d/0x400 net/socket.c:925 call_write_iter include/linux/fs.h:1778 [inline] aio_write+0x291/0x4e0 fs/aio.c:1553 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! io_submit_one fs/aio.c:1641 [inline] do_io_submit+0xb66/0x1290 fs/aio.c:1709 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 SYSC_io_submit fs/aio.c:1734 [inline] SyS_io_submit+0xb/0x10 fs/aio.c:1731 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x465a59 RSP: 002b:00007f7e9e3cd188 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1 RAX: ffffffffffffffda RBX: 000000000055bf40 RCX: 0000000000465a59 RDX: 0000000020000080 RSI: 0000000000000001 RDI: 00007f7e9e3ac000 RBP: 00000000004af682 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf40 R13: 00007ffda9ba55cf R14: 00007f7e9e3cd300 R15: 0000000000022000 Allocated by task 18: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:551 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 __do_kmalloc mm/slab.c:3720 [inline] __kmalloc+0x15d/0x410 mm/slab.c:3729 kmalloc include/linux/slab.h:493 [inline] kzalloc include/linux/slab.h:661 [inline] neigh_alloc net/core/neighbour.c:324 [inline] __neigh_create+0x1c2/0x1810 net/core/neighbour.c:499 ip6_finish_output2+0x7fd/0x2070 net/ipv6/ip6_output.c:117 ip6_finish_output+0x54f/0xcc0 net/ipv6/ip6_output.c:192 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip6_output+0x1b3/0x610 net/ipv6/ip6_output.c:209 dst_output include/net/dst.h:470 [inline] NF_HOOK include/linux/netfilter.h:250 [inline] mld_sendpack+0x635/0xe10 net/ipv6/mcast.c:1660 mld_send_initial_cr.part.15+0xd7/0x110 net/ipv6/mcast.c:2077 mld_send_initial_cr net/ipv6/mcast.c:2090 [inline] ipv6_mc_dad_complete+0x14d/0x1a0 net/ipv6/mcast.c:2084 addrconf_dad_completed+0x850/0xb90 net/ipv6/addrconf.c:4061 addrconf_dad_work+0x61f/0xfa0 net/ipv6/addrconf.c:3992 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 worker_thread+0xcc/0xee0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready Freed by task 0: batman_adv: batadv0: Interface activated: batadv_slave_0 (stack is not available) batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! The buggy address belongs to the object at ffff88809c2e3680 which belongs to the cache kmalloc-1024 of size 1024 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1 The buggy address is located 63 bytes to the right of 1024-byte region [ffff88809c2e3680, ffff88809c2e3a80) batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! The buggy address belongs to the page: page:ffffea000270b880 count:1 mapcount:0 mapping:ffff88809c2e2000 index:0x0 compound_mapcount: 0 flags: 0xfff00000008100(slab|head) raw: 00fff00000008100 ffff88809c2e2000 0000000000000000 0000000100000007 raw: ffffea00026e8da0 ffffea00026fe720 ffff88813fe60ac0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809c2e3980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88809c2e3a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88809c2e3a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff88809c2e3b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809c2e3b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================