bisecting fixing commit since 27ce4f2a6817e38ca74c643d47a96359f6cc0c1c building syzkaller on 1bf9a662c66aa432ff2fe3bf2562578cef626c09 testing commit 27ce4f2a6817e38ca74c643d47a96359f6cc0c1c with gcc (GCC) 8.1.0 kernel signature: 2084ce15ffaf39d52c846f720c6bcf4130919deea4c193507a0bc2fc43c65aa9 run #0: crashed: KASAN: use-after-free 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: use-after-free 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: use-after-free Read in ipvlan_queue_xmit run #8: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #9: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit testing current HEAD 3f2ecb86cb909da0b9157fd2952ad79924cbe5ae testing commit 3f2ecb86cb909da0b9157fd2952ad79924cbe5ae with gcc (GCC) 8.1.0 kernel signature: fc360cbe3ff98fd7fb08bcb0d67e43844d5b969827bfdc6c2738243592df46fd run #0: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #1: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #2: crashed: KASAN: slab-out-of-bounds 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: 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: slab-out-of-bounds Read in ipvlan_queue_xmit run #9: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit revisions tested: 2, total time: 22m57.25750364s (build: 16m39.088353419s, test: 5m40.477617505s) the crash still happens on HEAD commit msg: Linux 4.14.212 crash: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit 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 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 batman_adv: batadv0: Interface activated: batadv_slave_0 Read of size 4 at addr ffff8881e73917bf by task syz-executor.3/9159 CPU: 1 PID: 9159 Comm: syz-executor.3 Not tainted 4.14.212-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/0x1f1 lib/dump_stack.c:58 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report.cold.7+0x11a/0x2d4 mm/kasan/report.c:409 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1 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 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! ipvlan_start_xmit+0x4a/0x150 drivers/net/ipvlan/ipvlan_main.c:286 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! __netdev_start_xmit include/linux/netdevice.h:4039 [inline] netdev_start_xmit include/linux/netdevice.h:4048 [inline] packet_direct_xmit+0x3ed/0x630 net/packet/af_packet.c:269 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1 packet_snd.isra.30+0x9ba/0x2650 net/packet/af_packet.c:3024 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! packet_sendmsg+0x1007/0x27d0 net/packet/af_packet.c:3049 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:656 SYSC_sendto net/socket.c:1763 [inline] SyS_sendto+0x1e4/0x2c0 net/socket.c:1731 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45deb9 RSP: 002b:00007fd8877e1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 000000000002e940 RCX: 000000000045deb9 RDX: 000000000000000e RSI: 0000000020000000 RDI: 0000000000000004 RBP: 000000000118c020 R08: 0000000000000000 R09: ffffffffffffff09 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bfd4 R13: 00007fffa9c1dd2f R14: 00007fd8877e29c0 R15: 000000000118bfd4 Allocated by task 8288: 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 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 kmem_cache_alloc_trace+0x152/0x3f0 mm/slab.c:3618 kmalloc include/linux/slab.h:488 [inline] kzalloc include/linux/slab.h:661 [inline] aa_alloc_task_context+0x44/0x60 security/apparmor/context.c:40 apparmor_cred_prepare+0x16/0x90 security/apparmor/lsm.c:84 security_prepare_creds+0x6a/0xa0 security/security.c:1008 prepare_creds+0x29e/0x350 kernel/cred.c:282 prepare_exec_creds+0xc/0xd0 kernel/cred.c:301 prepare_bprm_creds+0x59/0x100 fs/exec.c:1407 do_execveat_common.isra.14+0x29a/0x1d70 fs/exec.c:1748 do_execve+0x1e/0x20 fs/exec.c:1860 call_usermodehelper_exec_async+0x2de/0x530 kernel/umh.c:109 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Freed by task 17: 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_slab_free+0xab/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcc/0x270 mm/slab.c:3815 kzfree+0x26/0x30 mm/slab_common.c:1453 aa_free_task_context+0xa5/0xe0 security/apparmor/context.c:54 apparmor_cred_free+0x34/0x70 security/apparmor/lsm.c:58 security_cred_free+0x66/0xa0 security/security.c:1003 put_cred_rcu+0xd0/0x2d0 kernel/cred.c:117 __rcu_reclaim kernel/rcu/rcu.h:195 [inline] rcu_do_batch kernel/rcu/tree.c:2699 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline] rcu_process_callbacks+0x7a5/0x11e0 kernel/rcu/tree.c:2946 __do_softirq+0x246/0x9b5 kernel/softirq.c:288 The buggy address belongs to the object at ffff8881e7391780 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 31 bytes to the right of 32-byte region [ffff8881e7391780, ffff8881e73917a0) The buggy address belongs to the page: page:ffffea00079ce440 count:1 mapcount:0 mapping:ffff8881e7391000 index:0xffff8881e7391fc1 flags: 0x17ff00000000100(slab) raw: 017ff00000000100 ffff8881e7391000 ffff8881e7391fc1 000000010000003f raw: ffffea0007a246a0 ffffea0007a23f60 ffff8881f60001c0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881e7391680: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff8881e7391700: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc >ffff8881e7391780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ^ ffff8881e7391800: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff8881e7391880: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ==================================================================