Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] handle_userfault.cold.18+0x3e/0x51 fs/userfaultfd.c:323 protocol 0000 is buggy, dev sit0 ================================================================== BUG: KASAN: use-after-free in skb_copy_datagram_iter+0x898/0x8f0 net/core/datagram.c:399 Read of size 1 at addr ffff8801beed9c40 by task syz-executor4/27859 [] do_anonymous_page mm/memory.c:2747 [inline] [] handle_pte_fault mm/memory.c:3508 [inline] [] __handle_mm_fault mm/memory.c:3597 [inline] [] handle_mm_fault+0x221d/0x28e0 mm/memory.c:3634 [] __do_page_fault+0x5af/0xd50 arch/x86/mm/fault.c:1407 [] do_page_fault+0x27/0x30 arch/x86/mm/fault.c:1470 [] page_fault+0x28/0x30 arch/x86/entry/entry_64.S:951 [] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb CPU: 1 PID: 27859 Comm: syz-executor4 Not tainted 4.9.96-g320d53a #7 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801a010f838 ffffffff81eb0b69 ffffea0006fbb600 ffff8801beed9c40 0000000000000000 ffff8801beed9c40 ffff8801a010fe30 ffff8801a010f870 ffffffff8156540b ffff8801beed9c40 0000000000000001 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] print_address_description+0x6c/0x234 mm/kasan/report.c:256 [] kasan_report_error mm/kasan/report.c:355 [inline] [] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412 [] __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 [] skb_copy_datagram_iter+0x898/0x8f0 net/core/datagram.c:399 [] skb_copy_datagram_msg include/linux/skbuff.h:3049 [inline] [] packet_recvmsg+0x266/0xf40 net/packet/af_packet.c:3350 [] sock_recvmsg_nosec net/socket.c:737 [inline] [] sock_recvmsg+0xc6/0x110 net/socket.c:744 [] ___sys_recvmsg+0x242/0x550 net/socket.c:2128 [] __sys_recvmsg+0xd6/0x190 net/socket.c:2173 [] SYSC_recvmsg net/socket.c:2185 [inline] [] SyS_recvmsg+0x2d/0x50 net/socket.c:2180 [] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Allocated by task 27875: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack+0x43/0xd0 mm/kasan/kasan.c:505 set_track mm/kasan/kasan.c:517 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:609 kasan_slab_alloc+0x12/0x20 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] __kmalloc_track_caller+0xdc/0x2b0 mm/slub.c:4232 __kmalloc_reserve.isra.37+0x33/0xc0 net/core/skbuff.c:138 __alloc_skb+0x11a/0x600 net/core/skbuff.c:231 alloc_skb include/linux/skbuff.h:919 [inline] alloc_skb_with_frags+0xaf/0x520 net/core/skbuff.c:4678 sock_alloc_send_pskb+0x5a9/0x750 net/core/sock.c:1893 packet_alloc_skb net/packet/af_packet.c:2810 [inline] packet_snd net/packet/af_packet.c:2901 [inline] packet_sendmsg+0x1599/0x44e0 net/packet/af_packet.c:2978 sock_sendmsg_nosec net/socket.c:635 [inline] sock_sendmsg+0xcc/0x110 net/socket.c:645 ___sys_sendmsg+0x6fc/0x840 net/socket.c:1969 __sys_sendmsg+0xd9/0x190 net/socket.c:2003 SYSC_sendmsg net/socket.c:2014 [inline] SyS_sendmsg+0x2d/0x50 net/socket.c:2010 do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282 entry_SYSCALL_64_after_swapgs+0x5d/0xdb Freed by task 27875: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack+0x43/0xd0 mm/kasan/kasan.c:505 set_track mm/kasan/kasan.c:517 [inline] kasan_slab_free+0x72/0xc0 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] kfree+0xfb/0x310 mm/slub.c:3878 skb_free_head+0x8b/0xb0 net/core/skbuff.c:580 skb_release_data+0x329/0x400 net/core/skbuff.c:611 skb_release_all+0x4a/0x60 net/core/skbuff.c:670 __kfree_skb+0x15/0x20 net/core/skbuff.c:684 kfree_skb+0xcc/0x340 net/core/skbuff.c:705 sit_tunnel_xmit+0xfb/0x2590 net/ipv6/sit.c:1033 __netdev_start_xmit include/linux/netdevice.h:4062 [inline] netdev_start_xmit include/linux/netdevice.h:4071 [inline] xmit_one net/core/dev.c:2955 [inline] dev_hard_start_xmit+0x197/0x8b0 net/core/dev.c:2971 __dev_queue_xmit+0x19a5/0x2080 net/core/dev.c:3451 dev_queue_xmit+0x17/0x20 net/core/dev.c:3484 packet_snd net/packet/af_packet.c:2953 [inline] packet_sendmsg+0x1f17/0x44e0 net/packet/af_packet.c:2978 sock_sendmsg_nosec net/socket.c:635 [inline] sock_sendmsg+0xcc/0x110 net/socket.c:645 ___sys_sendmsg+0x6fc/0x840 net/socket.c:1969 __sys_sendmsg+0xd9/0x190 net/socket.c:2003 SYSC_sendmsg net/socket.c:2014 [inline] SyS_sendmsg+0x2d/0x50 net/socket.c:2010 do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282 entry_SYSCALL_64_after_swapgs+0x5d/0xdb The buggy address belongs to the object at ffff8801beed9b80 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 192 bytes inside of 512-byte region [ffff8801beed9b80, ffff8801beed9d80) The buggy address belongs to the page: page:ffffea0006fbb600 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 flags: 0x8000000000004080(slab|head) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801beed9b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801beed9b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801beed9c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801beed9c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801beed9d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================