KMSAN: uninit-value in pppol2tp_connect

From: syzbot
Date: Mon Apr 23 2018 - 04:24:40 EST


syzbot hit the following crash on commit
a7f95e9c8a95e9fbb388c3999b61a17667cd3bbe (Sat Apr 21 13:50:22 2018 +0000)
kmsan: disable assembly checksums
syzbot dashboard link:

So far this crash happened 3 times on
C reproducer:
syzkaller reproducer:
Raw console output:
Kernel config:
compiler: clang version 7.0.0 (trunk 329391)

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Reported-by: syzbot+a70ac890b23b1bf29f5c@xxxxxxxxxxxxxxxxxxxxxxxxx
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BUG: KMSAN: uninit-value in pppol2tp_connect+0x258/0x1c50 net/l2tp/l2tp_ppp.c:622
CPU: 1 PID: 4524 Comm: syzkaller735385 Not tainted 4.16.0+ #85
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
pppol2tp_connect+0x258/0x1c50 net/l2tp/l2tp_ppp.c:622
SYSC_connect+0x41a/0x510 net/socket.c:1639
SyS_connect+0x54/0x80 net/socket.c:1620
do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
RIP: 0033:0x445559
RSP: 002b:00007f0b96f0ddb8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00000000006dac24 RCX: 0000000000445559
RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000000000003
RBP: 00000000006dac20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffec2b0929f R14: 00007f0b96f0e9c0 R15: 0000000000000001

Local variable description: ----address@SYSC_connect
Variable was created at:
SYSC_connect+0x6f/0x510 net/socket.c:1622
SyS_connect+0x54/0x80 net/socket.c:1620

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