Re: [syzbot] KMSAN: uninit-value in INET_ECN_decapsulate (2)

[Eric Dumazet]

On 3/30/21 3:26 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    29ad81a1 arch/x86: add missing include to sparsemem.h
> git tree:       https://github.com/google/kmsan.git master
> console output: https://syzkaller.appspot.com/x/log.txt?x=166fe481d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=b573c14b733efb1c
> dashboard link: https://syzkaller.appspot.com/bug?extid=5e9c61d74e52a82b8ace
> compiler:       Debian clang version 11.0.1-2
> userspace arch: i386
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5e9c61d74e52a82b8ace@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> =====================================================
> BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:236 [inline]
> BUG: KMSAN: uninit-value in INET_ECN_decapsulate+0x329/0x1db0 include/net/inet_ecn.h:258
> CPU: 1 PID: 9058 Comm: syz-executor.1 Not tainted 5.11.0-rc7-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  <IRQ>
>  __dump_stack lib/dump_stack.c:79 [inline]
>  dump_stack+0x21c/0x280 lib/dump_stack.c:120
>  kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118
>  __msan_warning+0x5f/0xa0 mm/kmsan/kmsan_instr.c:197
>  __INET_ECN_decapsulate include/net/inet_ecn.h:236 [inline]
>  INET_ECN_decapsulate+0x329/0x1db0 include/net/inet_ecn.h:258
>  geneve_rx+0x216e/0x29d0 include/net/inet_ecn.h:304
>  geneve_udp_encap_recv+0x1055/0x1340 drivers/net/geneve.c:377
>  udp_queue_rcv_one_skb+0x1943/0x1af0 net/ipv4/udp.c:2095
>  udp_queue_rcv_skb+0x286/0x1040 net/ipv4/udp.c:2169
>  udp_unicast_rcv_skb net/ipv4/udp.c:2327 [inline]
>  __udp4_lib_rcv+0x3a1f/0x58f0 net/ipv4/udp.c:2396
>  udp_rcv+0x5c/0x70 net/ipv4/udp.c:2567
>  ip_protocol_deliver_rcu+0x572/0xc50 net/ipv4/ip_input.c:204
>  ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline]
>  NF_HOOK include/linux/netfilter.h:301 [inline]
>  ip_local_deliver+0x585/0x8d0 net/ipv4/ip_input.c:252
>  dst_input include/net/dst.h:447 [inline]
>  ip_rcv_finish net/ipv4/ip_input.c:428 [inline]
>  NF_HOOK include/linux/netfilter.h:301 [inline]
>  ip_rcv+0x599/0x820 net/ipv4/ip_input.c:539
>  __netif_receive_skb_one_core net/core/dev.c:5323 [inline]
>  __netif_receive_skb+0x1ec/0x640 net/core/dev.c:5437
>  process_backlog+0x517/0xbd0 net/core/dev.c:6328
>  napi_poll+0x428/0x15c0 net/core/dev.c:6806
>  net_rx_action+0x34c/0xd30 net/core/dev.c:6889
>  __do_softirq+0x1b9/0x715 kernel/softirq.c:343
>  asm_call_irq_on_stack+0xf/0x20
>  </IRQ>
>  __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
>  run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
>  do_softirq_own_stack+0x6e/0x90 arch/x86/kernel/irq_64.c:77
>  do_softirq kernel/softirq.c:246 [inline]
>  __local_bh_enable_ip+0x184/0x1d0 kernel/softirq.c:196
>  local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
>  rcu_read_unlock_bh include/linux/rcupdate.h:737 [inline]
>  __dev_queue_xmit+0x3b3e/0x45c0 net/core/dev.c:4178
>  dev_queue_xmit+0x4b/0x60 net/core/dev.c:4184
>  packet_snd net/packet/af_packet.c:3006 [inline]
>  packet_sendmsg+0x8778/0x9a60 net/packet/af_packet.c:3031
>  sock_sendmsg_nosec net/socket.c:652 [inline]
>  sock_sendmsg net/socket.c:672 [inline]
>  __sys_sendto+0x9ea/0xc60 net/socket.c:1975
>  __do_sys_sendto net/socket.c:1987 [inline]
>  __se_sys_sendto+0x107/0x130 net/socket.c:1983
>  __ia32_sys_sendto+0x6e/0x90 net/socket.c:1983
>  do_syscall_32_irqs_on arch/x86/entry/common.c:79 [inline]
>  __do_fast_syscall_32+0x102/0x160 arch/x86/entry/common.c:141
>  do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:166
>  do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:209
>  entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
> RIP: 0023:0xf7f84549
> Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
> RSP: 002b:00000000f557e5fc EFLAGS: 00000296 ORIG_RAX: 0000000000000171
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000980
> RDX: 000000000000000e RSI: 0000000000000000 RDI: 00000000200002c0
> RBP: 0000000000000014 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> 
> Uninit was created at:
>  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:121 [inline]
>  kmsan_internal_poison_shadow+0x5c/0xf0 mm/kmsan/kmsan.c:104
>  kmsan_slab_alloc+0x8d/0xe0 mm/kmsan/kmsan_hooks.c:76
>  slab_alloc_node mm/slub.c:2907 [inline]
>  __kmalloc_node_track_caller+0xa37/0x1430 mm/slub.c:4527
>  __kmalloc_reserve net/core/skbuff.c:142 [inline]
>  __alloc_skb+0x2f8/0xb30 net/core/skbuff.c:210
>  alloc_skb include/linux/skbuff.h:1099 [inline]
>  alloc_skb_with_frags+0x1f3/0xc10 net/core/skbuff.c:5894
>  sock_alloc_send_pskb+0xdc1/0xf90 net/core/sock.c:2348
>  packet_alloc_skb net/packet/af_packet.c:2854 [inline]
>  packet_snd net/packet/af_packet.c:2949 [inline]
>  packet_sendmsg+0x6aab/0x9a60 net/packet/af_packet.c:3031
>  sock_sendmsg_nosec net/socket.c:652 [inline]
>  sock_sendmsg net/socket.c:672 [inline]
>  __sys_sendto+0x9ea/0xc60 net/socket.c:1975
>  __do_sys_sendto net/socket.c:1987 [inline]
>  __se_sys_sendto+0x107/0x130 net/socket.c:1983
>  __ia32_sys_sendto+0x6e/0x90 net/socket.c:1983
>  do_syscall_32_irqs_on arch/x86/entry/common.c:79 [inline]
>  __do_fast_syscall_32+0x102/0x160 arch/x86/entry/common.c:141
>  do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:166
>  do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:209
>  entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
> =====================================================
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
> 
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> 

#syz fix: net: geneve: check skb is large enough for IPv4/IPv6 header