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BUG: KMSAN: uninit-value in tcp_parse_options+0x1161/0x1c70 net/ipv4/tcp_input.c:3720
CPU: 0 PID: 7948 Comm: syz-executor4 Not tainted 4.16.0+ #87
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+0x185/0x1d0 lib/dump_stack.c:53
 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
 tcp_parse_options+0x1161/0x1c70 net/ipv4/tcp_input.c:3720
 tcp_fast_parse_options net/ipv4/tcp_input.c:3858 [inline]
 tcp_validate_incoming+0x4f1/0x2790 net/ipv4/tcp_input.c:5184
 tcp_rcv_state_process+0xb40/0x65f0 net/ipv4/tcp_input.c:5875
 tcp_v4_do_rcv+0xb26/0xd90 net/ipv4/tcp_ipv4.c:1491
 sk_backlog_rcv include/net/sock.h:908 [inline]
 __release_sock+0x2d6/0x680 net/core/sock.c:2271
 release_sock+0x97/0x2a0 net/core/sock.c:2786
 inet_shutdown+0x5c3/0x640 net/ipv4/af_inet.c:855
 SYSC_shutdown+0x2a3/0x400 net/socket.c:1901
 SyS_shutdown+0x44/0x60 net/socket.c:1892
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x455389
RSP: 002b:00007f44e736ac68 EFLAGS: 00000246 ORIG_RAX: 0000000000000030
RAX: ffffffffffffffda RBX: 00007f44e736b6d4 RCX: 0000000000455389
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000611 R14: 00000000006fc238 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188
 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314
 kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321
 slab_post_alloc_hook mm/slab.h:445 [inline]
 slab_alloc_node mm/slub.c:2737 [inline]
 __kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369
 __kmalloc_reserve net/core/skbuff.c:138 [inline]
 __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206
 alloc_skb include/linux/skbuff.h:984 [inline]
 tcp_send_ack+0x18c/0x910 net/ipv4/tcp_output.c:3624
 __tcp_ack_snd_check net/ipv4/tcp_input.c:5040 [inline]
 tcp_ack_snd_check net/ipv4/tcp_input.c:5053 [inline]
 tcp_rcv_state_process+0x5785/0x65f0 net/ipv4/tcp_input.c:6052
 tcp_v4_do_rcv+0xb26/0xd90 net/ipv4/tcp_ipv4.c:1491
 sk_backlog_rcv include/net/sock.h:908 [inline]
 __release_sock+0x2d6/0x680 net/core/sock.c:2271
 release_sock+0x97/0x2a0 net/core/sock.c:2786
 inet_shutdown+0x5c3/0x640 net/ipv4/af_inet.c:855
 SYSC_shutdown+0x2a3/0x400 net/socket.c:1901
 SyS_shutdown+0x44/0x60 net/socket.c:1892
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
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