BUG: unable to handle kernel NULL pointer dereference in do_fast_syscall_32 (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    fb279f4e Merge branch 'i2c/for-current-fixed' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17d84f31e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=751a68849f797e8b
dashboard link: https://syzkaller.appspot.com/bug?extid=7f0cd10fb4b63c9e7046
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7f0cd10fb4b63c9e7046@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 95be5067 P4D 95be5067 PUD a6eaf067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 9527 Comm: syz-executor.3 Not tainted 5.6.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
RIP: 0010:do_fast_syscall_32+0x289/0xdfb arch/x86/entry/common.c:408
Code: 00 0f 85 a7 0a 00 00 48 89 ef ff 14 dd a0 79 00 88 48 8d 7d 50 48 ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 80 3c 11 00 <00> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
RSP: 0018:ffffc90002207f18 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00000000000000a2 RCX: 1ffff92000440ff5
RDX: dffffc0000000000 RSI: ffffffff8162df47 RDI: ffffc90002207fa8
RBP: ffffc90002207f58 R08: ffff8880613b2140 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000f7f3be39
R13: ffffffff8973b288 R14: ffffc90002207fd8 R15: ffffc90002207fd0
FS:  0000000000000000(0000) GS:ffff8880ae700000(0063) knlGS:00000000096ba900
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000a70f6000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
Modules linked in:
CR2: 0000000000000000
---[ end trace e097d86a02851000 ]---
RIP: 0010:do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
RIP: 0010:do_fast_syscall_32+0x289/0xdfb arch/x86/entry/common.c:408
Code: 00 0f 85 a7 0a 00 00 48 89 ef ff 14 dd a0 79 00 88 48 8d 7d 50 48 ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 80 3c 11 00 <00> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
RSP: 0018:ffffc90002207f18 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00000000000000a2 RCX: 1ffff92000440ff5
RDX: dffffc0000000000 RSI: ffffffff8162df47 RDI: ffffc90002207fa8
RBP: ffffc90002207f58 R08: ffff8880613b2140 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000f7f3be39
R13: ffffffff8973b288 R14: ffffc90002207fd8 R15: ffffc90002207fd0
FS:  0000000000000000(0000) GS:ffff8880ae700000(0063) knlGS:00000000096ba900
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000a70f6000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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