KMSAN: uninit-value in ip_vs_lblcr_check_expire

From: syzbot
Date: Mon Apr 23 2018 - 09:28:33 EST

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Hello,

syzbot hit the following crash on https://github.com/google/kmsan.git/master commit
d2d741e5d1898dfde1a75ea3d29a9a3e2edf0617 (Sun Apr 22 15:05:22 2018 +0000)
kmsan: add initialization for shmem pages
syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=3dfdea57819073a04f21

So far this crash happened 2 times on https://github.com/google/kmsan.git/master.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output: https://syzkaller.appspot.com/x/log.txt?id=6285034612850688
Kernel config: https://syzkaller.appspot.com/x/.config?id=328654897048964367
compiler: clang version 7.0.0 (trunk 329391)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+3dfdea57819073a04f21@xxxxxxxxxxxxxxxxxxxxxxxxx
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RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000014
R13: 00000000000004f3 R14: 00000000006fa768 R15: 0000000000000000
==================================================================
BUG: KMSAN: uninit-value in ip_vs_lblcr_check_expire+0x1551/0x1600 net/netfilter/ipvs/ip_vs_lblcr.c:479
CPU: 0 PID: 13883 Comm: syz-executor4 Not tainted 4.16.0+ #86
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__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
ip_vs_lblcr_check_expire+0x1551/0x1600 net/netfilter/ipvs/ip_vs_lblcr.c:479
call_timer_fn+0x26a/0x5a0 kernel/time/timer.c:1326
expire_timers kernel/time/timer.c:1363 [inline]
__run_timers+0xda7/0x11c0 kernel/time/timer.c:1666
run_timer_softirq+0x43/0x70 kernel/time/timer.c:1692
__do_softirq+0x56d/0x93d kernel/softirq.c:285
invoke_softirq kernel/softirq.c:365 [inline]
irq_exit+0x202/0x240 kernel/softirq.c:405
exiting_irq+0xe/0x10 arch/x86/include/asm/apic.h:541
smp_apic_timer_interrupt+0x64/0x90 arch/x86/kernel/apic/apic.c:1055
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:857
</IRQ>
RIP: 0010:native_restore_fl arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/irqflags.h:78 [inline]
RIP: 0010:dump_stack+0x1af/0x1d0 lib/dump_stack.c:58
RSP: 0018:ffff880156a2ef00 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff12
RAX: ffff8801fddc2590 RBX: ffff88014f62c418 RCX: ffff880000000000
RDX: ffff8801fd9c2590 RSI: aaaaaaaaaaaab000 RDI: ffffea0000000000
RBP: ffff880156a2ef48 R08: 0000000001080000 R09: 0000000000000002
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000cf000109
R13: 0000000000000286 R14: 0000000000000000 R15: 0000000000000000
fail_dump lib/fault-inject.c:51 [inline]
should_fail+0x87b/0xab0 lib/fault-inject.c:149
should_failslab+0x279/0x2a0 mm/failslab.c:32
slab_pre_alloc_hook mm/slab.h:422 [inline]
slab_alloc_node mm/slub.c:2663 [inline]
slab_alloc mm/slub.c:2745 [inline]
kmem_cache_alloc+0x136/0xb90 mm/slub.c:2750
dst_alloc+0x295/0x860 net/core/dst.c:104
__ip6_dst_alloc net/ipv6/route.c:361 [inline]
ip6_rt_cache_alloc+0x445/0xd00 net/ipv6/route.c:1061
ip6_pol_route+0x3f19/0x5da0 net/ipv6/route.c:1751
ip6_pol_route_output+0xe6/0x110 net/ipv6/route.c:1892
fib6_rule_lookup+0x494/0x720 net/ipv6/fib6_rules.c:87
ip6_route_output_flags+0x4fa/0x590 net/ipv6/route.c:1920
ip6_dst_lookup_tail+0x2fe/0x1a60 net/ipv6/ip6_output.c:992
ip6_dst_lookup_flow+0xfc/0x270 net/ipv6/ip6_output.c:1093
rawv6_sendmsg+0x1b05/0x4fb0 net/ipv6/raw.c:908
inet_sendmsg+0x48d/0x740 net/ipv4/af_inet.c:764
sock_sendmsg_nosec net/socket.c:630 [inline]
sock_sendmsg net/socket.c:640 [inline]
___sys_sendmsg+0xec0/0x1310 net/socket.c:2046
__sys_sendmsg net/socket.c:2080 [inline]
SYSC_sendmsg+0x2a3/0x3d0 net/socket.c:2091
SyS_sendmsg+0x54/0x80 net/socket.c:2087
do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x455389
RSP: 002b:00007fa5b1000c68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fa5b10016d4 RCX: 0000000000455389
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000014
R13: 00000000000004f3 R14: 00000000006fa768 R15: 0000000000000000

Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:814
kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:868
__alloc_pages_nodemask+0xf5b/0x5dc0 mm/page_alloc.c:4283
alloc_pages_current+0x6b5/0x970 mm/mempolicy.c:2055
alloc_pages include/linux/gfp.h:494 [inline]
kmalloc_order mm/slab_common.c:1164 [inline]
kmalloc_order_trace+0xb9/0x390 mm/slab_common.c:1175
kmalloc_large include/linux/slab.h:446 [inline]
__kmalloc+0x332/0x350 mm/slub.c:3778
kmalloc include/linux/slab.h:517 [inline]
ip_vs_lblcr_init_svc+0x57/0x310 net/netfilter/ipvs/ip_vs_lblcr.c:518
ip_vs_bind_scheduler+0xa4/0x1e0 net/netfilter/ipvs/ip_vs_sched.c:51
ip_vs_add_service+0xa91/0x1d70 net/netfilter/ipvs/ip_vs_ctl.c:1265
do_ip_vs_set_ctl+0x25c8/0x2790 net/netfilter/ipvs/ip_vs_ctl.c:2457
nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
nf_setsockopt+0x476/0x4d0 net/netfilter/nf_sockopt.c:115
ip_setsockopt+0x24b/0x2b0 net/ipv4/ip_sockglue.c:1261
dccp_setsockopt+0x1c3/0x1f0 net/dccp/proto.c:576
sock_common_setsockopt+0x136/0x170 net/core/sock.c:2975
SYSC_setsockopt+0x4b8/0x570 net/socket.c:1849
SyS_setsockopt+0x76/0xa0 net/socket.c:1828
do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
==================================================================

---
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Next message: Martijn Coenen: "Re: KASAN: use-after-free Read in binder_release_work"
Previous message: syzbot: "KMSAN: uninit-value in ip_vs_lblc_check_expire"
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