================================================================== BUG: KASAN: use-after-free in tcp_highest_sack_seq include/net/tcp.h:1706 [inline] BUG: KASAN: use-after-free in tcp_ack+0x42bb/0x4fd0 net/ipv4/tcp_input.c:3537 Read of size 4 at addr ffff8801cc6f3828 by task syz-executor4/6533 CPU: 1 PID: 6533 Comm: syz-executor4 Not tainted 4.14.0-next-20171113+ #41 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+0x194/0x257 lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x25b/0x340 mm/kasan/report.c:409 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 tcp_highest_sack_seq include/net/tcp.h:1706 [inline] tcp_ack+0x42bb/0x4fd0 net/ipv4/tcp_input.c:3537 tcp_rcv_established+0x672/0x18a0 net/ipv4/tcp_input.c:5439 tcp_v4_do_rcv+0x2ab/0x7d0 net/ipv4/tcp_ipv4.c:1468 tcp_v4_rcv+0x24e5/0x2f80 net/ipv4/tcp_ipv4.c:1729 ip_local_deliver_finish+0x2e2/0xba0 net/ipv4/ip_input.c:216 NF_HOOK include/linux/netfilter.h:250 [inline] ip_local_deliver+0x1ce/0x6e0 net/ipv4/ip_input.c:257 dst_input include/net/dst.h:466 [inline] ip_rcv_finish+0x887/0x19a0 net/ipv4/ip_input.c:397 NF_HOOK include/linux/netfilter.h:250 [inline] ip_rcv+0xc3f/0x1820 net/ipv4/ip_input.c:493 __netif_receive_skb_core+0x1a3e/0x3450 net/core/dev.c:4478 __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4543 process_backlog+0x203/0x740 net/core/dev.c:5222 napi_poll net/core/dev.c:5620 [inline] net_rx_action+0x792/0x1910 net/core/dev.c:5686 __do_softirq+0x29d/0xbb2 kernel/softirq.c:285 invoke_softirq kernel/softirq.c:365 [inline] irq_exit+0x1d3/0x210 kernel/softirq.c:405 exiting_irq arch/x86/include/asm/apic.h:540 [inline] smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052 apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:791 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:777 [inline] RIP: 0010:lock_is_held_type+0x18b/0x210 kernel/locking/lockdep.c:4044 RSP: 0018:ffff8801ce33f9c8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff11 RAX: dffffc0000000000 RBX: 0000000000000286 RCX: 0000000000000000 RDX: 1ffffffff0bd96b1 RSI: 00000000ffffffff RDI: 0000000000000286 RBP: ffff8801ce33f9e8 R08: ffffed0039c67f11 R09: 1ffff10039c67ecf R10: ffff8801c6086400 R11: 0000000000000000 R12: ffff8801c6086400 R13: 0000000000000000 R14: 1ffff10039c67f74 R15: 0000000000000000 lock_is_held include/linux/lockdep.h:437 [inline] rcu_read_lock_sched_held+0x108/0x120 kernel/rcu/update.c:117 trace_module_request include/trace/events/module.h:107 [inline] __request_module+0x964/0xc00 kernel/kmod.c:169 __sock_create+0x5f9/0x850 net/socket.c:1242 sock_create net/socket.c:1301 [inline] SYSC_socketpair net/socket.c:1373 [inline] SyS_socketpair+0x115/0x640 net/socket.c:1352 entry_SYSCALL_64_fastpath+0x1f/0x96 RIP: 0033:0x452879 RSP: 002b:00007f72a08bcbe8 EFLAGS: 00000212 ORIG_RAX: 0000000000000035 RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452879 RDX: ffffffffffffffff RSI: 0000000000000804 RDI: 0000000000000013 RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000020b74000 R11: 0000000000000212 R12: 0000000000000000 R13: 0000000000a6f7ff R14: 00007f72a08bd9c0 R15: 0000000000000000 Allocated by task 6521: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc_node+0x144/0x760 mm/slab.c:3638 __alloc_skb+0xf1/0x780 net/core/skbuff.c:193 alloc_skb_fclone include/linux/skbuff.h:1023 [inline] sk_stream_alloc_skb+0x11d/0x900 net/ipv4/tcp.c:870 tcp_sendmsg_locked+0x1341/0x3b80 net/ipv4/tcp.c:1299 tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1461 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763 sock_sendmsg_nosec net/socket.c:632 [inline] sock_sendmsg+0xca/0x110 net/socket.c:642 SYSC_sendto+0x358/0x5a0 net/socket.c:1749 SyS_sendto+0x40/0x50 net/socket.c:1717 entry_SYSCALL_64_fastpath+0x1f/0x96 Freed by task 6521: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3492 [inline] kmem_cache_free+0x77/0x280 mm/slab.c:3750 kfree_skbmem+0xdd/0x1d0 net/core/skbuff.c:603 __kfree_skb+0x1d/0x20 net/core/skbuff.c:642 tcp_collapse_one+0x114/0x1e0 net/ipv4/tcp_input.c:4685 tcp_collapse+0x935/0xd20 net/ipv4/tcp_input.c:4799 tcp_prune_queue net/ipv4/tcp_input.c:4915 [inline] tcp_try_rmem_schedule+0xaab/0x1820 net/ipv4/tcp_input.c:4352 tcp_data_queue+0x7bd/0x3dd0 net/ipv4/tcp_input.c:4596 tcp_rcv_established+0x844/0x18a0 net/ipv4/tcp_input.c:5448 tcp_v4_do_rcv+0x2ab/0x7d0 net/ipv4/tcp_ipv4.c:1468 sk_backlog_rcv include/net/sock.h:909 [inline] __release_sock+0x124/0x360 net/core/sock.c:2264 release_sock+0xa4/0x2a0 net/core/sock.c:2778 tcp_sendmsg+0x3a/0x50 net/ipv4/tcp.c:1462 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763 sock_sendmsg_nosec net/socket.c:632 [inline] sock_sendmsg+0xca/0x110 net/socket.c:642 ___sys_sendmsg+0x75b/0x8a0 net/socket.c:2048 __sys_sendmsg+0xe5/0x210 net/socket.c:2082 SYSC_sendmsg net/socket.c:2093 [inline] SyS_sendmsg+0x2d/0x50 net/socket.c:2089 entry_SYSCALL_64_fastpath+0x1f/0x96 The buggy address belongs to the object at ffff8801cc6f3800 which belongs to the cache skbuff_fclone_cache of size 456 The buggy address is located 40 bytes inside of 456-byte region [ffff8801cc6f3800, ffff8801cc6f39c8) The buggy address belongs to the page: page:ffffea000731bcc0 count:1 mapcount:0 mapping:ffff8801cc6f3080 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffff8801cc6f3080 0000000000000000 0000000100000006 raw: ffffea00071e59e0 ffffea00072e4aa0 ffff8801d9ca0500 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801cc6f3700: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc ffff8801cc6f3780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8801cc6f3800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801cc6f3880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801cc6f3900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================