batman_adv: batadv0: The MTU of interface vlan4 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem. batman_adv: batadv0: Not using interface vlan4 (retrying later): interface not active ================================================================== BUG: KASAN: use-after-free in br_dev_xmit+0x12b3/0x13e0 net/bridge/br_device.c:68 Read of size 2 at addr ffff8880983392ce by task swapper/1/0 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256 kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354 kasan_report mm/kasan/report.c:412 [inline] __asan_report_load_n_noabort+0x8b/0xa0 mm/kasan/report.c:443 br_dev_xmit+0x12b3/0x13e0 net/bridge/br_device.c:68 __netdev_start_xmit include/linux/netdevice.h:4349 [inline] netdev_start_xmit include/linux/netdevice.h:4363 [inline] xmit_one net/core/dev.c:3256 [inline] dev_hard_start_xmit+0x1a8/0x920 net/core/dev.c:3272 __dev_queue_xmit+0x269d/0x2e00 net/core/dev.c:3838 vlan_dev_hard_start_xmit+0x38f/0x800 net/8021q/vlan_dev.c:131 __netdev_start_xmit include/linux/netdevice.h:4349 [inline] netdev_start_xmit include/linux/netdevice.h:4363 [inline] xmit_one net/core/dev.c:3256 [inline] dev_hard_start_xmit+0x1a8/0x920 net/core/dev.c:3272 __dev_queue_xmit+0x269d/0x2e00 net/core/dev.c:3838 neigh_connected_output+0x3e8/0x5e0 net/core/neighbour.c:1403 neigh_output include/net/neighbour.h:501 [inline] ip6_finish_output2+0x113d/0x2290 net/ipv6/ip6_output.c:120 ip6_finish_output+0x89b/0x10f0 net/ipv6/ip6_output.c:192 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip6_output+0x205/0x770 net/ipv6/ip6_output.c:209 dst_output include/net/dst.h:455 [inline] NF_HOOK include/linux/netfilter.h:289 [inline] mld_sendpack+0x674/0x1060 net/ipv6/mcast.c:1681 mld_send_cr net/ipv6/mcast.c:1977 [inline] mld_ifc_timer_expire+0x616/0xdf0 net/ipv6/mcast.c:2476 call_timer_fn+0x177/0x700 kernel/time/timer.c:1338 expire_timers+0x243/0x4e0 kernel/time/timer.c:1375 __run_timers kernel/time/timer.c:1696 [inline] run_timer_softirq+0x21c/0x670 kernel/time/timer.c:1709 __do_softirq+0x265/0x980 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x215/0x260 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x136/0x550 arch/x86/kernel/apic/apic.c:1098 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61 Code: 48 89 df e8 f4 20 7f f9 e9 2e ff ff ff 48 89 df e8 e7 20 7f f9 eb 82 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 14 43 4e 00 fb f4 90 e9 07 00 00 00 0f 00 2d 04 43 4e 00 f4 c3 90 90 41 56 41 55 RSP: 0018:ffff8880b5a9fd40 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff13e3054 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffff8880b5a86c44 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff89f18290 R13: 1ffff11016b53fb2 R14: 0000000000000000 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0x49/0x310 arch/x86/kernel/process.c:557 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x2ec/0x4b0 kernel/sched/idle.c:263 cpu_startup_entry+0xc5/0xe0 kernel/sched/idle.c:369 start_secondary+0x435/0x5c0 arch/x86/kernel/smpboot.c:271 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 Allocated by task 0: __do_kmalloc_node mm/slab.c:3689 [inline] __kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3703 __kmalloc_reserve net/core/skbuff.c:137 [inline] __alloc_skb+0xae/0x560 net/core/skbuff.c:205 alloc_skb include/linux/skbuff.h:995 [inline] alloc_skb_with_frags+0x92/0x570 net/core/skbuff.c:5333 sock_alloc_send_pskb+0x6e1/0x830 net/core/sock.c:2108 mld_newpack+0x1d2/0x760 net/ipv6/mcast.c:1609 add_grhead+0x265/0x330 net/ipv6/mcast.c:1712 add_grec+0xe3c/0x10b0 net/ipv6/mcast.c:1843 mld_send_cr net/ipv6/mcast.c:1969 [inline] mld_ifc_timer_expire+0x5a2/0xdf0 net/ipv6/mcast.c:2476 call_timer_fn+0x177/0x700 kernel/time/timer.c:1338 expire_timers+0x243/0x4e0 kernel/time/timer.c:1375 __run_timers kernel/time/timer.c:1696 [inline] run_timer_softirq+0x21c/0x670 kernel/time/timer.c:1709 __do_softirq+0x265/0x980 kernel/softirq.c:292 Freed by task 0: __cache_free mm/slab.c:3503 [inline] kfree+0xcc/0x210 mm/slab.c:3822 skb_free_head net/core/skbuff.c:563 [inline] pskb_expand_head+0x327/0xf20 net/core/skbuff.c:1506 __skb_cow include/linux/skbuff.h:2977 [inline] skb_cow_head include/linux/skbuff.h:3011 [inline] __vlan_insert_inner_tag include/linux/if_vlan.h:346 [inline] vlan_insert_inner_tag include/linux/if_vlan.h:416 [inline] vlan_insert_tag include/linux/if_vlan.h:441 [inline] vlan_insert_tag_set_proto include/linux/if_vlan.h:460 [inline] __allowed_ingress net/bridge/br_vlan.c:437 [inline] br_allowed_ingress+0x376/0xed0 net/bridge/br_vlan.c:514 br_dev_xmit+0x3e5/0x13e0 net/bridge/br_device.c:64 __netdev_start_xmit include/linux/netdevice.h:4349 [inline] netdev_start_xmit include/linux/netdevice.h:4363 [inline] xmit_one net/core/dev.c:3256 [inline] dev_hard_start_xmit+0x1a8/0x920 net/core/dev.c:3272 __dev_queue_xmit+0x269d/0x2e00 net/core/dev.c:3838 vlan_dev_hard_start_xmit+0x38f/0x800 net/8021q/vlan_dev.c:131 __netdev_start_xmit include/linux/netdevice.h:4349 [inline] netdev_start_xmit include/linux/netdevice.h:4363 [inline] xmit_one net/core/dev.c:3256 [inline] dev_hard_start_xmit+0x1a8/0x920 net/core/dev.c:3272 __dev_queue_xmit+0x269d/0x2e00 net/core/dev.c:3838 neigh_connected_output+0x3e8/0x5e0 net/core/neighbour.c:1403 neigh_output include/net/neighbour.h:501 [inline] ip6_finish_output2+0x113d/0x2290 net/ipv6/ip6_output.c:120 ip6_finish_output+0x89b/0x10f0 net/ipv6/ip6_output.c:192 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip6_output+0x205/0x770 net/ipv6/ip6_output.c:209 dst_output include/net/dst.h:455 [inline] NF_HOOK include/linux/netfilter.h:289 [inline] mld_sendpack+0x674/0x1060 net/ipv6/mcast.c:1681 mld_send_cr net/ipv6/mcast.c:1977 [inline] mld_ifc_timer_expire+0x616/0xdf0 net/ipv6/mcast.c:2476 call_timer_fn+0x177/0x700 kernel/time/timer.c:1338 expire_timers+0x243/0x4e0 kernel/time/timer.c:1375 __run_timers kernel/time/timer.c:1696 [inline] run_timer_softirq+0x21c/0x670 kernel/time/timer.c:1709 __do_softirq+0x265/0x980 kernel/softirq.c:292 The buggy address belongs to the object at ffff8880983392c0 which belongs to the cache kmalloc-2048 of size 2048 The buggy address is located 14 bytes inside of 2048-byte region [ffff8880983392c0, ffff888098339ac0) The buggy address belongs to the page: page:ffffea000260ce00 count:1 mapcount:0 mapping:ffff88813bff0c40 index:0x0 compound_mapcount: 0 flags: 0xfff00000008100(slab|head) raw: 00fff00000008100 ffffea0002448508 ffffea0002d35a88 ffff88813bff0c40 raw: 0000000000000000 ffff8880983381c0 0000000100000003 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888098339180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888098339200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888098339280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff888098339300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888098339380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ---------------- Code disassembly (best guess): 0: 48 89 df mov %rbx,%rdi 3: e8 f4 20 7f f9 callq 0xf97f20fc 8: e9 2e ff ff ff jmpq 0xffffff3b d: 48 89 df mov %rbx,%rdi 10: e8 e7 20 7f f9 callq 0xf97f20fc 15: eb 82 jmp 0xffffff99 17: 90 nop 18: 90 nop 19: 90 nop 1a: 90 nop 1b: 90 nop 1c: e9 07 00 00 00 jmpq 0x28 21: 0f 00 2d 14 43 4e 00 verw 0x4e4314(%rip) # 0x4e433c 28: fb sti 29: f4 hlt * 2a: c3 retq <-- trapping instruction 2b: 90 nop 2c: e9 07 00 00 00 jmpq 0x38 31: 0f 00 2d 04 43 4e 00 verw 0x4e4304(%rip) # 0x4e433c 38: f4 hlt 39: c3 retq 3a: 90 nop 3b: 90 nop 3c: 41 56 push %r14 3e: 41 55 push %r13