================================================================== BUG: KASAN: use-after-free in nf_ct_ipv4_gather_frags net/ipv4/netfilter/nf_defrag_ipv4.c:35 [inline] BUG: KASAN: use-after-free in ipv4_conntrack_defrag net/ipv4/netfilter/nf_defrag_ipv4.c:84 [inline] BUG: KASAN: use-after-free in ipv4_conntrack_defrag+0x2ae/0x2f0 net/ipv4/netfilter/nf_defrag_ipv4.c:61 Write of size 4 at addr ffff88017234ed08 by task syz-executor2/2837 CPU: 1 PID: 2837 Comm: syz-executor2 Not tainted 4.9.154+ #25 ffff8801db707948 ffffffff81b47411 0000000000000001 ffffea0005c8d380 ffff88017234ed08 0000000000000004 ffffffff826028de ffff8801db707980 ffffffff81502615 0000000000000001 ffff88017234ed08 ffff88017234ed08 Call Trace: [ 2766.682153] [] __dump_stack lib/dump_stack.c:15 [inline] [ 2766.682153] [] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [] print_address_description+0x6f/0x238 mm/kasan/report.c:256 [] kasan_report_error mm/kasan/report.c:355 [inline] [] kasan_report mm/kasan/report.c:412 [inline] [] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:397 [] __asan_report_store4_noabort+0x17/0x20 mm/kasan/report.c:437 [] nf_ct_ipv4_gather_frags net/ipv4/netfilter/nf_defrag_ipv4.c:35 [inline] [] ipv4_conntrack_defrag net/ipv4/netfilter/nf_defrag_ipv4.c:84 [inline] [] ipv4_conntrack_defrag+0x2ae/0x2f0 net/ipv4/netfilter/nf_defrag_ipv4.c:61 [] nf_iterate+0x12e/0x310 net/netfilter/core.c:324 [] nf_hook_slow+0x114/0x1f0 net/netfilter/core.c:355 [] nf_hook_thresh include/linux/netfilter.h:191 [inline] [] NF_HOOK_THRESH include/linux/netfilter.h:230 [inline] [] NF_HOOK include/linux/netfilter.h:255 [inline] [] ip_rcv+0xbdf/0x1040 net/ipv4/ip_input.c:488 [] __netif_receive_skb_core+0x1156/0x2990 net/core/dev.c:4289 [] __netif_receive_skb+0x58/0x1c0 net/core/dev.c:4327 [] process_backlog+0x1e8/0x610 net/core/dev.c:4952 [] napi_poll net/core/dev.c:5253 [inline] [] net_rx_action+0x3aa/0xdd0 net/core/dev.c:5318 [] __do_softirq+0x22d/0x964 kernel/softirq.c:288 [] do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:843 [ 2766.863400] [] do_softirq.part.0+0x62/0x70 kernel/softirq.c:332 [] do_softirq+0x18/0x20 kernel/softirq.c:320 [] netif_rx_ni+0xbe/0x310 net/core/dev.c:3919 [] tun_get_user+0xcd2/0x2430 drivers/net/tun.c:1330 [] tun_chr_write_iter+0xda/0x190 drivers/net/tun.c:1353 [] do_iter_readv_writev+0x3d9/0x4b0 fs/read_write.c:695 [] do_readv_writev+0x2ed/0x7a0 fs/read_write.c:871 [] vfs_writev+0x89/0xc0 fs/read_write.c:910 [] do_writev+0xe9/0x260 fs/read_write.c:943 [] SYSC_writev fs/read_write.c:1016 [inline] [] SyS_writev+0x28/0x30 fs/read_write.c:1013 [] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Allocated by task 2837: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack mm/kasan/kasan.c:505 [inline] set_track mm/kasan/kasan.c:517 [inline] kasan_kmalloc.part.0+0x62/0xf0 mm/kasan/kasan.c:609 kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:594 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:547 slab_post_alloc_hook mm/slab.h:417 [inline] slab_alloc_node mm/slub.c:2715 [inline] slab_alloc mm/slub.c:2723 [inline] kmem_cache_alloc+0xd5/0x2b0 mm/slub.c:2728 kmem_cache_alloc_node include/linux/slab.h:364 [inline] __alloc_skb+0xe7/0x5e0 net/core/skbuff.c:219 alloc_skb include/linux/skbuff.h:924 [inline] alloc_skb_with_frags+0xb0/0x4f0 net/core/skbuff.c:4711 sock_alloc_send_pskb+0x5ec/0x760 net/core/sock.c:1894 tun_alloc_skb drivers/net/tun.c:1166 [inline] tun_get_user+0x53b/0x2430 drivers/net/tun.c:1263 tun_chr_write_iter+0xda/0x190 drivers/net/tun.c:1353 do_iter_readv_writev+0x3d9/0x4b0 fs/read_write.c:695 do_readv_writev+0x2ed/0x7a0 fs/read_write.c:871 vfs_writev+0x89/0xc0 fs/read_write.c:910 do_writev+0xe9/0x260 fs/read_write.c:943 SYSC_writev fs/read_write.c:1016 [inline] SyS_writev+0x28/0x30 fs/read_write.c:1013 do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 entry_SYSCALL_64_after_swapgs+0x5d/0xdb Freed by task 2837: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack mm/kasan/kasan.c:505 [inline] set_track mm/kasan/kasan.c:517 [inline] kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:582 slab_free_hook mm/slub.c:1355 [inline] slab_free_freelist_hook mm/slub.c:1377 [inline] slab_free mm/slub.c:2958 [inline] kmem_cache_free+0xbe/0x310 mm/slub.c:2980 kfree_skbmem+0x9f/0x100 net/core/skbuff.c:623 __kfree_skb net/core/skbuff.c:685 [inline] kfree_skb+0xd4/0x350 net/core/skbuff.c:705 ip_frag_queue net/ipv4/ip_fragment.c:505 [inline] ip_defrag+0x620/0x3bc0 net/ipv4/ip_fragment.c:690 nf_ct_ipv4_gather_frags net/ipv4/netfilter/nf_defrag_ipv4.c:31 [inline] ipv4_conntrack_defrag net/ipv4/netfilter/nf_defrag_ipv4.c:84 [inline] ipv4_conntrack_defrag+0x1b4/0x2f0 net/ipv4/netfilter/nf_defrag_ipv4.c:61 nf_iterate+0x12e/0x310 net/netfilter/core.c:324 nf_hook_slow+0x114/0x1f0 net/netfilter/core.c:355 nf_hook_thresh include/linux/netfilter.h:191 [inline] NF_HOOK_THRESH include/linux/netfilter.h:230 [inline] NF_HOOK include/linux/netfilter.h:255 [inline] ip_rcv+0xbdf/0x1040 net/ipv4/ip_input.c:488 __netif_receive_skb_core+0x1156/0x2990 net/core/dev.c:4289 __netif_receive_skb+0x58/0x1c0 net/core/dev.c:4327 process_backlog+0x1e8/0x610 net/core/dev.c:4952 napi_poll net/core/dev.c:5253 [inline] net_rx_action+0x3aa/0xdd0 net/core/dev.c:5318 __do_softirq+0x22d/0x964 kernel/softirq.c:288 The buggy address belongs to the object at ffff88017234ec80 which belongs to the cache skbuff_head_cache of size 224 The buggy address is located 136 bytes inside of 224-byte region [ffff88017234ec80, ffff88017234ed60) The buggy address belongs to the page: page:ffffea0005c8d380 count:1 mapcount:0 mapping: (null) index:0x0 flags: 0x4000000000000080(slab) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88017234ec00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff88017234ec80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88017234ed00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff88017234ed80: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 ffff88017234ee00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================