KMSAN: uninit-value in gre_rcv (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: eb2e67596de2 kmsan: minor code cleanup
git tree: https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=12b763fa400000
kernel config: https://syzkaller.appspot.com/x/.config?x=94a9ed72288f7fef
dashboard link: https://syzkaller.appspot.com/bug?extid=841c053d026900055032
compiler: clang version 8.0.0 (trunk 339414)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12aac356400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16346711400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+841c05...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0
==================================================================
BUG: KMSAN: uninit-value in __arch_swab32
arch/x86/include/uapi/asm/swab.h:10 [inline]
BUG: KMSAN: uninit-value in __fswab32 include/uapi/linux/swab.h:59 [inline]
BUG: KMSAN: uninit-value in erspan_rcv net/ipv4/ip_gre.c:285 [inline]
BUG: KMSAN: uninit-value in gre_rcv+0x11d0/0x1920 net/ipv4/ip_gre.c:425
CPU: 0 PID: 4713 Comm: syz-executor382 Not tainted 4.19.0-rc4+ #58
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x2f6/0x430 lib/dump_stack.c:113
kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:917
__msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:500
__arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
__fswab32 include/uapi/linux/swab.h:59 [inline]
erspan_rcv net/ipv4/ip_gre.c:285 [inline]
gre_rcv+0x11d0/0x1920 net/ipv4/ip_gre.c:425
gre_rcv+0x2d5/0x3b0 net/ipv4/gre_demux.c:142
ip_local_deliver_finish+0x90e/0xfa0 net/ipv4/ip_input.c:215
NF_HOOK include/linux/netfilter.h:287 [inline]
ip_local_deliver+0x438/0x4d0 net/ipv4/ip_input.c:256
dst_input include/net/dst.h:450 [inline]
ip_rcv_finish net/ipv4/ip_input.c:415 [inline]
NF_HOOK include/linux/netfilter.h:287 [inline]
ip_rcv+0x65f/0x6d0 net/ipv4/ip_input.c:524
__netif_receive_skb_one_core net/core/dev.c:4891 [inline]
__netif_receive_skb net/core/dev.c:5001 [inline]
process_backlog+0xd89/0x11a0 net/core/dev.c:5807
napi_poll net/core/dev.c:6227 [inline]
net_rx_action+0x935/0x1c00 net/core/dev.c:6293
__do_softirq+0x614/0xa72 kernel/softirq.c:292
do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1055
</IRQ>
do_softirq kernel/softirq.c:336 [inline]
__local_bh_enable_ip+0x119/0x150 kernel/softirq.c:189
local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
rcu_read_unlock_bh include/linux/rcupdate.h:723 [inline]
ip_finish_output2+0x13cd/0x14f0 net/ipv4/ip_output.c:231
ip_do_fragment+0x37b8/0x3fd0 net/ipv4/ip_output.c:678
ip_fragment+0x249/0x3f0 net/ipv4/ip_output.c:561
ip_finish_output+0xfbb/0x10a0 net/ipv4/ip_output.c:315
NF_HOOK_COND include/linux/netfilter.h:276 [inline]
ip_output+0x50f/0x5d0 net/ipv4/ip_output.c:405
dst_output include/net/dst.h:444 [inline]
ip_local_out net/ipv4/ip_output.c:124 [inline]
ip_send_skb+0x178/0x350 net/ipv4/ip_output.c:1441
udp_send_skb+0x10b9/0x18d0 net/ipv4/udp.c:829
udp_push_pending_frames net/ipv4/udp.c:857 [inline]
udp_sendmsg+0xac6/0x3cd0 net/ipv4/udp.c:1148
udpv6_sendmsg+0x12e2/0x4cf0 net/ipv6/udp.c:1196
inet_sendmsg+0x4c5/0x7d0 net/ipv4/af_inet.c:798
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg net/socket.c:631 [inline]
__sys_sendto+0x868/0xa30 net/socket.c:1786
__do_sys_sendto net/socket.c:1798 [inline]
__se_sys_sendto+0x107/0x130 net/socket.c:1794
__x64_sys_sendto+0x6e/0x90 net/socket.c:1794
do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x441319
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 db 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff698f4638 EFLAGS: 00000286 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000441319
RDX: 000000000000000e RSI: 0000000020000100 RDI: 0000000000000003
RBP: 00000000006cc018 R08: 0000000020000180 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000402280
R13: 0000000000402310 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:255 [inline]
kmsan_save_stack mm/kmsan/kmsan.c:270 [inline]
kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:572
kmsan_memcpy_origins+0x13d/0x1b0 mm/kmsan/kmsan.c:396
__msan_memcpy+0xc3/0x130 mm/kmsan/kmsan_instr.c:286
pskb_expand_head+0x49f/0x1e10 net/core/skbuff.c:1470
__skb_cow include/linux/skbuff.h:2911 [inline]
skb_cow_head include/linux/skbuff.h:2945 [inline]
ip_tunnel_xmit+0x3217/0x3870 net/ipv4/ip_tunnel.c:771
__gre_xmit net/ipv4/ip_gre.c:454 [inline]
erspan_xmit+0x1af6/0x3380 net/ipv4/ip_gre.c:752
__netdev_start_xmit include/linux/netdevice.h:4287 [inline]
netdev_start_xmit include/linux/netdevice.h:4296 [inline]
xmit_one net/core/dev.c:3216 [inline]
dev_hard_start_xmit+0x68b/0xd50 net/core/dev.c:3232
sch_direct_xmit+0x52b/0x860 net/sched/sch_generic.c:327
qdisc_restart net/sched/sch_generic.c:390 [inline]
__qdisc_run+0x1ab7/0x3490 net/sched/sch_generic.c:398
qdisc_run include/net/pkt_sched.h:120 [inline]
__dev_xmit_skb net/core/dev.c:3411 [inline]
__dev_queue_xmit+0x1bc3/0x3c60 net/core/dev.c:3770
dev_queue_xmit+0x4b/0x60 net/core/dev.c:3835
neigh_resolve_output+0xaa2/0xb40 net/core/neighbour.c:1364
neigh_output include/net/neighbour.h:483 [inline]
ip_finish_output2+0x13b7/0x14f0 net/ipv4/ip_output.c:229
ip_do_fragment+0x37b8/0x3fd0 net/ipv4/ip_output.c:678
ip_fragment+0x249/0x3f0 net/ipv4/ip_output.c:561
ip_finish_output+0xfbb/0x10a0 net/ipv4/ip_output.c:315
NF_HOOK_COND include/linux/netfilter.h:276 [inline]
ip_output+0x50f/0x5d0 net/ipv4/ip_output.c:405
dst_output include/net/dst.h:444 [inline]
ip_local_out net/ipv4/ip_output.c:124 [inline]
ip_send_skb+0x178/0x350 net/ipv4/ip_output.c:1441
udp_send_skb+0x10b9/0x18d0 net/ipv4/udp.c:829
udp_push_pending_frames net/ipv4/udp.c:857 [inline]
udp_sendmsg+0xac6/0x3cd0 net/ipv4/udp.c:1148
udpv6_sendmsg+0x12e2/0x4cf0 net/ipv6/udp.c:1196
inet_sendmsg+0x4c5/0x7d0 net/ipv4/af_inet.c:798
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg net/socket.c:631 [inline]
__sys_sendto+0x868/0xa30 net/socket.c:1786
__do_sys_sendto net/socket.c:1798 [inline]
__se_sys_sendto+0x107/0x130 net/socket.c:1794
__x64_sys_sendto+0x6e/0x90 net/socket.c:1794
do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7

Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:255 [inline]
kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:180
kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91
kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan_hooks.c:100
slab_post_alloc_hook mm/slab.h:446 [inline]
slab_alloc_node mm/slub.c:2718 [inline]
__kmalloc_node_track_caller+0xb55/0x1380 mm/slub.c:4351
__kmalloc_reserve net/core/skbuff.c:138 [inline]
__alloc_skb+0x40d/0xe50 net/core/skbuff.c:206
alloc_skb include/linux/skbuff.h:996 [inline]
alloc_skb_with_frags+0x1d0/0xac0 net/core/skbuff.c:5273
sock_alloc_send_pskb+0xe28/0x1420 net/core/sock.c:2082
sock_alloc_send_skb+0xca/0xe0 net/core/sock.c:2099
__ip_append_data+0x2d54/0x4460 net/ipv4/ip_output.c:981
ip_append_data+0x2fb/0x440 net/ipv4/ip_output.c:1196
udp_sendmsg+0x6f9/0x3cd0 net/ipv4/udp.c:1142
udpv6_sendmsg+0x12e2/0x4cf0 net/ipv6/udp.c:1196
inet_sendmsg+0x4c5/0x7d0 net/ipv4/af_inet.c:798
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg net/socket.c:631 [inline]
__sys_sendto+0x868/0xa30 net/socket.c:1786
__do_sys_sendto net/socket.c:1798 [inline]
__se_sys_sendto+0x107/0x130 net/socket.c:1794
__x64_sys_sendto+0x6e/0x90 net/socket.c:1794
do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.