unsafe follow_pfn usage
WARNING: CPU: 1 PID: 12669 at mm/memory.c:4818 unsafe_follow_pfn+0x20f/0x260 mm/memory.c:4818
Modules linked in:
CPU: 1 PID: 12669 Comm: syz-executor.3 Not tainted 5.12.0-rc5-next-20210401-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:unsafe_follow_pfn+0x20f/0x260 mm/memory.c:4818
Code: 8b 7c 24 20 49 89 6d 00 e8 5e e8 66 07 e9 30 ff ff ff e8 54 df ca ff 48 c7 c7 e0 23 76 89 c6 05 a9 44 0a 0c 01 e8 c2 2a 23 07 <0f> 0b e9 71 fe ff ff 41 bc ea ff ff ff e9 06 ff ff ff e8 2a 92 0f
RSP: 0018:ffffc9000201f660 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 1ffff92000403ecc RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815c1cc5 RDI: fffff52000403ebe
RBP: ffff888028ea7c60 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815bbb2e R11: 0000000000000000 R12: 0000000021000000
R13: ffff888032394010 R14: 0000000000000000 R15: 0000000000000110
FS:  00007f656db0a700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000056c000 CR3: 00000000193cf000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 get_vaddr_frames+0x337/0x600 drivers/media/common/videobuf2/frame_vector.c:72
 vb2_create_framevec+0x55/0xc0 drivers/media/common/videobuf2/videobuf2-memops.c:50
 vb2_vmalloc_get_userptr+0xce/0x4c0 drivers/media/common/videobuf2/videobuf2-vmalloc.c:90
 __prepare_userptr+0x342/0x15f0 drivers/media/common/videobuf2/videobuf2-core.c:1128
 __buf_prepare+0x635/0x7d0 drivers/media/common/videobuf2/videobuf2-core.c:1367
 vb2_core_qbuf+0xa9d/0x11c0 drivers/media/common/videobuf2/videobuf2-core.c:1658
 vb2_qbuf+0x135/0x1a0 drivers/media/common/videobuf2/videobuf2-v4l2.c:820
 vb2_ioctl_qbuf+0xfb/0x140 drivers/media/common/videobuf2/videobuf2-v4l2.c:1050
 v4l_qbuf drivers/media/v4l2-core/v4l2-ioctl.c:2027 [inline]
 v4l_qbuf+0x92/0xc0 drivers/media/v4l2-core/v4l2-ioctl.c:2021
 __video_do_ioctl+0xb94/0xe20 drivers/media/v4l2-core/v4l2-ioctl.c:2951
 video_usercopy+0x253/0x1300 drivers/media/v4l2-core/v4l2-ioctl.c:3297
 v4l2_ioctl+0x1b3/0x250 drivers/media/v4l2-core/v4l2-dev.c:366
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f656db0a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000020000140 RSI: 00000000c058560f RDI: 0000000000000004
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffc7fe2960f R14: 00007f656db0a300 R15: 0000000000022000