linux-kernel - BUG: pagefault on kernel address ADDR in non-whitelisted uaccess

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Message-ID: <000000000000fd734c05799d3c90@google.com>
Date:   Thu, 01 Nov 2018 09:52:03 -0700
From:   syzbot <syzbot+0cc8e3cc63ca373722c6@...kaller.appspotmail.com>
To:     hverkuil@...all.nl, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, mchehab@...nel.org,
        syzkaller-bugs@...glegroups.com
Subject: BUG: pagefault on kernel address ADDR in non-whitelisted uaccess

Hello,

syzbot found the following crash on:

HEAD commit:    59fc453b21f7 Merge branch 'akpm' (patches from Andrew)
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=110e6633400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ea045471e4c756e8
dashboard link: https://syzkaller.appspot.com/bug?extid=0cc8e3cc63ca373722c6
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

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+0cc8e3cc63ca373722c6@...kaller.appspotmail.com

BUG: pagefault on kernel address 0xffffc9000efe5000 in non-whitelisted  
uaccess
kobject: 'ip6_vti0' (000000003ce0d4aa): calling ktype release
BUG: unable to handle kernel paging request at ffffc9000efe5000
device nr0. entered promiscuous mode
PGD 1da948067 P4D 1da948067 PUD 1da949067 PMD 1d214e067 PTE 0
kobject: 'ip6_vti0': free name
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 23205 Comm: syz-executor3 Not tainted 4.19.0+ #313
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:copy_user_enhanced_fast_string+0xe/0x20  
arch/x86/lib/copy_user_64.S:180
kobject: 'loop4' (0000000033c61cb9): kobject_uevent_env
Code: 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 1f 00 c3 0f 1f  
80 00 00 00 00 0f 1f 00 83 fa 40 0f 82 70 ff ff ff 89 d1 <f3> a4 31 c0 0f  
1f 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 83
RSP: 0018:ffff880194bc7688 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 00000000000fd200 RCX: 00000000000f5200
RDX: 00000000000fd200 RSI: ffffc9000efe5000 RDI: 00000000200080c0
RBP: ffff880194bc76c0 R08: 0000000000000000 R09: 0000000000003f48
kobject: 'loop4' (0000000033c61cb9): fill_kobj_path: path  
= '/devices/virtual/block/loop4'
R10: fffff52001e1b43f R11: ffffc9000f0da1ff R12: 00000000200fd2c0
R13: 00000000200000c0 R14: ffffc9000efdd000 R15: 00007ffffffff000
FS:  00007fb9545c0700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc9000efe5000 CR3: 00000001b7ae7000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  copy_to_user include/linux/uaccess.h:155 [inline]
  vidioc_g_fmt_vid_overlay+0x392/0x550  
drivers/media/platform/vivid/vivid-vid-cap.c:1074
  v4l_g_fmt+0x2ad/0x640 drivers/media/v4l2-core/v4l2-ioctl.c:1487
  __video_do_ioctl+0x519/0xf00 drivers/media/v4l2-core/v4l2-ioctl.c:2833
  video_usercopy+0x5c1/0x1760 drivers/media/v4l2-core/v4l2-ioctl.c:3013
  video_ioctl2+0x2c/0x33 drivers/media/v4l2-core/v4l2-ioctl.c:3057
  v4l2_ioctl+0x154/0x1b0 drivers/media/v4l2-core/v4l2-dev.c:364
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:501 [inline]
  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
  __do_sys_ioctl fs/ioctl.c:709 [inline]
  __se_sys_ioctl fs/ioctl.c:707 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457569
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb9545bfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569
RDX: 00000000200000c0 RSI: 00000000c0d05604 RDI: 0000000000000003
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb9545c06d4
R13: 00000000004c1acf R14: 00000000004d29c8 R15: 00000000ffffffff
Modules linked in:
CR2: ffffc9000efe5000
---[ end trace a02231e0facef4c4 ]---
RIP: 0010:copy_user_enhanced_fast_string+0xe/0x20  
arch/x86/lib/copy_user_64.S:180
Code: 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 1f 00 c3 0f 1f  
80 00 00 00 00 0f 1f 00 83 fa 40 0f 82 70 ff ff ff 89 d1 <f3> a4 31 c0 0f  
1f 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 83
RSP: 0018:ffff880194bc7688 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 00000000000fd200 RCX: 00000000000f5200
RDX: 00000000000fd200 RSI: ffffc9000efe5000 RDI: 00000000200080c0
RBP: ffff880194bc76c0 R08: 0000000000000000 R09: 0000000000003f48
R10: fffff52001e1b43f R11: ffffc9000f0da1ff R12: 00000000200fd2c0
R13: 00000000200000c0 R14: ffffc9000efdd000 R15: 00007ffffffff000
FS:  00007fb9545c0700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc9000efe5000 CR3: 00000001b7ae7000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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