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Subjectkernel BUG at lib/string.c:LINE! (3)

syzbot hit the following crash on upstream commit
3eb2ce825ea1ad89d20f7a3b5780df850e4be274 (Sun Mar 25 22:44:30 2018 +0000)
Linux 4.16-rc7
syzbot dashboard link:

So far this crash happened 2 times on upstream.
syzkaller reproducer:
Raw console output:
Kernel config:
compiler: gcc (GCC) 7.1.1 20170620
user-space arch: i386

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It will help syzbot understand when the bug is fixed. See footer for
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IPVS: ftp: loaded support on port[0] = 21
detected buffer overflow in memcpy
------------[ cut here ]------------
kernel BUG at lib/string.c:1052!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 4211 Comm: syz-executor0 Not tainted 4.16.0-rc7+ #277
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:fortify_panic+0x13/0x20 lib/string.c:1051
RSP: 0018:ffff8801bccaf8f0 EFLAGS: 00010286
RAX: 0000000000000022 RBX: 1ffff10037995f23 RCX: 0000000000000000
RDX: 0000000000000022 RSI: 1ffff10037995ed3 RDI: ffffed0037995f12
RBP: ffff8801bccaf8f0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000006 R11: 0000000000000000 R12: ffff8801bccaf998
R13: ffff8801bccaf938 R14: ffff8801bccafa58 R15: 000000000000fa00
FS: 0000000000000000(0000) GS:ffff8801db200000(0063) knlGS:0000000009f8f900
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000008138024 CR3: 00000001ccb50005 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
memcpy include/linux/string.h:344 [inline]
ucma_join_ip_multicast+0x37a/0x3c0 drivers/infiniband/core/ucma.c:1434
ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1649
__vfs_write+0xef/0x970 fs/read_write.c:480
vfs_write+0x189/0x510 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xef/0x220 fs/read_write.c:581
do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f3ec99
RSP: 002b:00000000ffe9b98c EFLAGS: 00000286 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000040
RDX: 0000000000000038 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b 48 89 df e8 b2 e8 e2 fb eb
de 55 48 89 fe 48 c7 c7 00 7b 98 86 48 89 e5 e8 55 48 94 fb <0f> 0b 90 90
90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 56
RIP: fortify_panic+0x13/0x20 lib/string.c:1051 RSP: ffff8801bccaf8f0
---[ end trace c61655b171bd6d64 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..

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