KMSAN: uninit-value in nf_flow_table_offload_setup

From: syzbot
Date: Sat Feb 22 2020 - 11:18:13 EST


Hello,

syzbot found the following crash on:

HEAD commit: 8bbbc5cf kmsan: don't compile memmove
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=17325b4ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=cd0e9a6b0e555cc3
dashboard link: https://syzkaller.appspot.com/bug?extid=8fbe17d9bdd5c8815211
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10c39881e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11924edde00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+8fbe17d9bdd5c8815211@xxxxxxxxxxxxxxxxxxxxxxxxx

batman_adv: batadv0: Interface activated: batadv_slave_1
=====================================================
BUG: KMSAN: uninit-value in list_splice include/linux/list.h:437 [inline]
BUG: KMSAN: uninit-value in nf_flow_table_block_setup net/netfilter/nf_flow_table_offload.c:826 [inline]
BUG: KMSAN: uninit-value in nf_flow_table_offload_setup+0x964/0xac0 net/netfilter/nf_flow_table_offload.c:883
CPU: 1 PID: 11672 Comm: syz-executor942 Not tainted 5.6.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c9/0x220 lib/dump_stack.c:118
kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
__msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
list_splice include/linux/list.h:437 [inline]
nf_flow_table_block_setup net/netfilter/nf_flow_table_offload.c:826 [inline]
nf_flow_table_offload_setup+0x964/0xac0 net/netfilter/nf_flow_table_offload.c:883
nft_register_flowtable_net_hooks net/netfilter/nf_tables_api.c:6185 [inline]
nf_tables_newflowtable+0x233c/0x3e30 net/netfilter/nf_tables_api.c:6302
nfnetlink_rcv_batch net/netfilter/nfnetlink.c:433 [inline]
nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:543 [inline]
nfnetlink_rcv+0x155e/0x3ab0 net/netfilter/nfnetlink.c:561
netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1328
netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg net/socket.c:672 [inline]
____sys_sendmsg+0x12b6/0x1350 net/socket.c:2343
___sys_sendmsg net/socket.c:2397 [inline]
__sys_sendmsg+0x451/0x5f0 net/socket.c:2430
__do_sys_sendmsg net/socket.c:2439 [inline]
__se_sys_sendmsg+0x97/0xb0 net/socket.c:2437
__x64_sys_sendmsg+0x4a/0x70 net/socket.c:2437
do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x443709
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 7b 10 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffe96ae538 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000443709
RDX: 0000000000000000 RSI: 0000000020003e00 RDI: 0000000000000003
RBP: 00007fffe96ae550 R08: 0000000001bbbbbb R09: 0000000001bbbbbb
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000404ca0 R14: 0000000000000000 R15: 0000000000000000

Local variable ----bo@nf_flow_table_offload_setup created at:
nf_flow_table_offload_setup+0xba/0xac0 net/netfilter/nf_flow_table_offload.c:876
nf_flow_table_offload_setup+0xba/0xac0 net/netfilter/nf_flow_table_offload.c:876
=====================================================


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