general protection fault in smc_getsockopt

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
6f70eb2b00eb416146247c65003d31f4df983ce0 (Mon Feb 26 21:22:45 2018 +0000)
Merge branch 'idr-2018-02-06' of
git://git.infradead.org/users/willy/linux-dax

So far this crash happened 9 times on net-next, upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.
user-space arch: i386

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Reported-by: syzbot+28a2c8...@syzkaller.appspotmail.com
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details.
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IPv4: Oversized IP packet from 127.0.0.1
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 9427 Comm: syz-executor5 Not tainted 4.16.0-rc3+ #241
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:smc_getsockopt+0x8b/0x110 net/smc/af_smc.c:1299
RSP: 0018:ffff8801bf057cc0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff85a3b1b6
RDX: 0000000000000005 RSI: ffffc900031ca000 RDI: 0000000000000028
RBP: ffff8801bf057cf0 R08: 0000000020000080 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cdc7dac0
R13: 0000000000000084 R14: 000000000000000b R15: 0000000020000100
FS: 0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f77a9b40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000008452798 CR3: 00000001c68ae004 CR4: 00000000001626e0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
C_SYSC_getsockopt net/compat.c:526 [inline]
compat_SyS_getsockopt+0x2ed/0x420 net/compat.c:506
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: 0023:0xf7fcec99
RSP: 002b:00000000f77a909c EFLAGS: 00000286 ORIG_RAX: 000000000000016d
RAX: ffffffffffffffda RBX: 0000000000000015 RCX: 0000000000000084
RDX: 000000000000000b RSI: 0000000020000100 RDI: 0000000020000080
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 8e 00 00 00 48 8b 9b 48 04 00 00 48
b8 00 00 00 00 00 fc ff df 48 8d 7b 28 48 89 fa 48 c1 ea 03 <80> 3c 02 00
75 5d 4c 8b 63 28 48 b8 00 00 00 00 00 fc ff df 49
RIP: smc_getsockopt+0x8b/0x110 net/smc/af_smc.c:1299 RSP: ffff8801bf057cc0
---[ end trace c4063c0ed61565c1 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

syzbot has found reproducer for the following crash on upstream commit
83beed7b2b26f232d782127792dd0cd4362fdc41 (Fri Apr 20 17:56:32 2018 +0000)
Merge branch 'fixes' of
git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=28a2c86cf19c81d871fa

So far this crash happened 59 times on net-next, upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6375334488309760
syzkaller reproducer:
https://syzkaller.appspot.com/x/repro.syz?id=6112997885870080
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=5942131738804224
Kernel config:
https://syzkaller.appspot.com/x/.config?id=1808800213120130118
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+28a2c8...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed.

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:

CPU: 0 PID: 4492 Comm: syzkaller771634 Not tainted 4.17.0-rc1+ #10

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011

RIP: 0010:smc_getsockopt+0x8b/0x120 net/smc/af_smc.c:1298
RSP: 0018:ffff8801d90b7cc0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000020000000
RDX: 0000000000000005 RSI: ffffffff873e3d16 RDI: 0000000000000028
RBP: ffff8801d90b7cf0 R08: 0000000020000040 R09: ffffed0036a05800
R10: ffffed0036a05800 R11: ffff8801b502c003 R12: ffff8801d90b7d40
R13: 0000000000000000 R14: 0000000000000008 R15: 0000000020000000
FS: 0000000002017880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000040 CR3: 00000001ac552000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__sys_getsockopt+0x1a5/0x370 net/socket.c:1940
__do_sys_getsockopt net/socket.c:1951 [inline]
__se_sys_getsockopt net/socket.c:1948 [inline]
__x64_sys_getsockopt+0xbe/0x150 net/socket.c:1948
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43fcf9
RSP: 002b:00007ffcb16b9c58 EFLAGS: 00000217 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fcf9
RDX: 0000000000000008 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000020000040 R09: 00000000004002c8
R10: 0000000020000000 R11: 0000000000000217 R12: 0000000000401620
R13: 00000000004016b0 R14: 0000000000000000 R15: 0000000000000000
Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 93 00 00 00 48 8b 9b 50 04 00 00 48

b8 00 00 00 00 00 fc ff df 48 8d 7b 28 48 89 fa 48 c1 ea 03 <80> 3c 02 00

75 62 48 b8 00 00 00 00 00 fc ff df 4c 8b 63 28 49
RIP: smc_getsockopt+0x8b/0x120 net/smc/af_smc.c:1298 RSP: ffff8801d90b7cc0
---[ end trace 7e67761582d7c7ee ]---