Mike Rapoport df2cc96e77 userfaultfd: prevent non-cooperative events vs mcopy_atomic races ... If a process monitored with userfaultfd changes it's memory mappings or forks() at the same time as uffd monitor fills the process memory with UFFDIO_COPY, the actual creation of page table entries and copying of the data in mcopy_atomic may happen either before of after the memory mapping modifications and there is no way for the uffd monitor to maintain consistent view of the process memory layout. For instance, let's consider fork() running in parallel with userfaultfd_copy(): process | uffd monitor ---------------------------------+------------------------------ fork() | userfaultfd_copy() ... | ... dup_mmap() | down_read(mmap_sem) down_write(mmap_sem) | /* create PTEs, copy data */ dup_uffd() | up_read(mmap_sem) copy_page_range() | up_write(mmap_sem) | dup_uffd_complete() | /* notify monitor */ | If the userfaultfd_copy() takes the mmap_sem first, the new page(s) will be present by the time copy_page_range() is called and they will appear in the child's memory mappings. However, if the fork() is the first to take the mmap_sem, the new pages won't be mapped in the child's address space. If the pages are not present and child tries to access them, the monitor will get page fault notification and everything is fine. However, if the pages *are present*, the child can access them without uffd noticing. And if we copy them into child it'll see the wrong data. Since we are talking about background copy, we'd need to decide whether the pages should be copied or not regardless #PF notifications. Since userfaultfd monitor has no way to determine what was the order, let's disallow userfaultfd_copy in parallel with the non-cooperative events. In such case we return -EAGAIN and the uffd monitor can understand that userfaultfd_copy() clashed with a non-cooperative event and take an appropriate action. Link: http://lkml.kernel.org/r/1527061324-19949-1-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Acked-by: Pavel Emelyanov <xemul@virtuozzo.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrei Vagin <avagin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2018-06-07 17:34:38 -07:00
..
9p	fs/9p: detect invalid options as much as possible	2018-06-07 17:34:34 -07:00
adfs	adfs_lookup: do not fail with ENOENT on negatives, use d_splice_alias()	2018-05-22 14:27:56 -04:00
affs	affs: fix potential memory leak when parsing option 'prefix'	2018-05-28 12:36:41 +02:00
afs	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2018-06-06 18:39:49 -07:00
autofs4	autofs: mount point create should honour passed in mode	2018-04-20 17:18:35 -07:00
befs	befs_lookup(): use d_splice_alias()	2018-05-21 14:30:07 -04:00
bfs	bfs_add_entry: pass name/len as qstr pointer	2018-05-22 14:27:50 -04:00
btrfs	for-4.18-tag	2018-06-04 14:29:13 -07:00
cachefiles	Merge branch 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2018-06-04 10:00:01 -07:00
ceph	ceph: fix iov_iter issues in ceph_direct_read_write()	2018-05-10 10:15:12 +02:00
cifs	some smb3 fixes for stable, as well as addition of ftrace hooks for cifs.ko, and improvements in compounding and smbdirect (RDMA)	2018-06-04 14:42:46 -07:00
coda	vfs: do bulk POLL* -> EPOLL* replacement	2018-02-11 14:34:03 -08:00
configfs	…
cramfs	cramfs_lookup(): use d_splice_alias()	2018-05-22 14:27:51 -04:00
crypto	fscrypt: log the crypto algorithm implementations	2018-05-20 16:36:00 -04:00
debugfs	debugfs: inode: debugfs_create_dir uses mode permission from parent	2018-05-14 16:48:18 +02:00
devpts	devpts: comment devpts_mntget()	2018-03-14 13:31:23 +01:00
dlm	dlm: remove O_NONBLOCK flag in sctp_connect_to_sock	2018-05-29 10:48:35 -05:00
ecryptfs	Merge branch 'fixes' of https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs into aio-base	2018-05-26 09:16:25 +02:00
efivarfs	efivarfs: Limit the rate for non-root to read files	2018-02-22 10:21:02 -08:00
efs	…
exofs	scsi/osd: remove the gfp argument to osd_start_request	2018-05-14 08:55:09 -06:00
exportfs	ovl: do not try to reconnect a disconnected origin dentry	2018-04-12 12:04:49 +02:00
ext2	Changes for 4.18:	2018-06-05 13:24:20 -07:00
ext4	Add bunch of cleanups, and add support for the Speck128/256	2018-06-05 15:15:32 -07:00
f2fs	Add bunch of cleanups, and add support for the Speck128/256	2018-06-05 15:15:32 -07:00
fat	vfat: simplify checks in vfat_lookup()	2018-05-13 12:09:14 -04:00
freevxfs	freevxfs_lookup(): use d_splice_alias()	2018-05-22 14:27:51 -04:00
fscache	proc: introduce proc_create_single{,_data}	2018-05-16 07:23:35 +02:00
fuse	fuse update for 4.18	2018-06-07 08:50:57 -07:00
gfs2	Changes for 4.18:	2018-06-05 13:24:20 -07:00
hfs	hfs: don't allow mounting over .../rsrc	2018-05-22 14:28:00 -04:00
hfsplus	Merge branch 'work.lookup' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2018-06-04 13:46:22 -07:00
hostfs	hostfs: rename do_rmdir() to hostfs_do_rmdir()	2018-04-02 20:15:53 +02:00
hpfs	…
hugetlbfs	hugetlbfs: fix bug in pgoff overflow checking	2018-04-05 21:36:21 -07:00
isofs	isofs: fix potential memory leak in mount option parsing	2018-04-16 09:47:41 +02:00
jbd2	jbd2: remove NULL check before calling kmem_cache_destroy()	2018-05-20 22:38:26 -04:00
jffs2	do d_instantiate/unlock_new_inode combinations safely	2018-05-11 15:36:37 -04:00
jfs	Merge branch 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2018-06-04 10:00:01 -07:00
kernfs	Driver core changes for 4.18-rc1	2018-06-05 16:29:19 -07:00
lockd	net: Drop pernet_operations::async	2018-03-27 13:18:09 -04:00
minix	minix_lookup: use d_splice_alias()	2018-05-22 14:27:52 -04:00
nfs	proc: introduce proc_create_net{,_data}	2018-05-16 07:24:30 +02:00
nfs_common	net: Drop pernet_operations::async	2018-03-27 13:18:09 -04:00
nfsd	for-4.18/block-20180603	2018-06-04 07:58:06 -07:00
nilfs2	do d_instantiate/unlock_new_inode combinations safely	2018-05-11 15:36:37 -04:00
nls	…
notify	fsnotify: fix ignore mask logic in send_to_group()	2018-04-13 15:52:49 +02:00
ntfs	ntfs: fix bogus __mark_inode_dirty(I_DIRTY_SYNC | I_DIRTY_DATASYNC) call	2018-03-28 01:39:02 -04:00
ocfs2	fs: ocfs2: use new return type vm_fault_t	2018-06-07 17:34:34 -07:00
omfs	omfs_lookup(): report IO errors, use d_splice_alias()	2018-05-22 14:27:58 -04:00
openpromfs	openpromfs: switch to d_splice_alias()	2018-05-22 14:27:57 -04:00
orangefs	orangefs: fixes and cleanups	2018-06-07 09:23:12 -07:00
overlayfs	ovl: use inode_insert5() to hash a newly created inode	2018-05-31 11:06:12 +02:00
proc	mm: mark pages in use for page tables	2018-06-07 17:34:37 -07:00
pstore	pstore: fix crypto dependencies without compression	2018-04-06 15:45:33 -07:00
qnx4	qnx4_lookup: use d_splice_alias()	2018-05-22 14:27:52 -04:00
qnx6	qnx6_lookup: switch to d_splice_alias()	2018-05-22 14:27:54 -04:00
quota	fs: quota: Replace GFP_ATOMIC with GFP_KERNEL in dquot_init	2018-04-09 17:48:54 +02:00
ramfs	…
reiserfs	Merge branch 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2018-06-04 10:00:01 -07:00
romfs	romfs_lookup: switch to d_splice_alias()	2018-05-22 14:27:55 -04:00
squashfs	…
sysfs	unfuck sysfs_mount()	2018-05-21 14:30:09 -04:00
sysv	sysv_lookup: use d_splice_alias()	2018-05-22 14:27:53 -04:00
tracefs	…
ubifs	Add bunch of cleanups, and add support for the Speck128/256	2018-06-05 15:15:32 -07:00
udf	\n	2018-06-07 09:36:29 -07:00
ufs	do d_instantiate/unlock_new_inode combinations safely	2018-05-11 15:36:37 -04:00
xfs	Changes for 4.18:	2018-06-05 13:24:20 -07:00
Kconfig	mm: restructure memfd code	2018-06-07 17:34:35 -07:00
Kconfig.binfmt	treewide: simplify Kconfig dependencies for removed archs	2018-03-26 15:55:57 +02:00
Makefile	split d_path() and friends into a separate file	2018-03-29 15:07:46 -04:00
aio.c	aio: sanitize the limit checking in io_submit(2)	2018-05-29 23:20:17 -04:00
anon_inodes.c	…
attr.c	fs: Allow superblock owner to replace invalid owners of inodes	2018-05-24 11:57:18 -05:00
bad_inode.c	…
binfmt_aout.c	exec: introduce finalize_exec() before start_thread()	2018-04-11 10:28:37 -07:00
binfmt_elf.c	fs, elf: don't complain MAP_FIXED_NOREPLACE unless -EEXIST error	2018-04-20 17:18:36 -07:00
binfmt_elf_fdpic.c	exec: introduce finalize_exec() before start_thread()	2018-04-11 10:28:37 -07:00
binfmt_em86.c	…
binfmt_flat.c	exec: introduce finalize_exec() before start_thread()	2018-04-11 10:28:37 -07:00
binfmt_misc.c	fs: add ksys_close() wrapper; remove in-kernel calls to sys_close()	2018-04-02 20:16:00 +02:00
binfmt_script.c	…
block_dev.c	fs: convert block_dev.c to bioset_init()	2018-05-30 15:33:32 -06:00
buffer.c	fs: move page_cache_seek_hole_data to iomap.c	2018-06-01 18:37:33 -07:00
char_dev.c	block, char_dev: Use correct format specifier for unsigned ints	2018-03-15 17:59:24 +01:00
compat.c	…
compat_binfmt_elf.c	…
compat_ioctl.c	…
coredump.c	…
d_path.c	split d_path() and friends into a separate file	2018-03-29 15:07:46 -04:00
dax.c	fs/dax.c: use new return type vm_fault_t	2018-06-07 17:34:33 -07:00
dcache.c	Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2018-06-04 10:14:28 -07:00
dcookies.c	fs: add do_lookup_dcookie() helper; remove in-kernel call to syscall	2018-04-02 20:15:39 +02:00
direct-io.c	block: consistently use GFP_NOIO instead of __GFP_NORECLAIM	2018-05-14 08:55:18 -06:00
drop_caches.c	…
eventfd.c	eventfd: switch to ->poll_mask	2018-05-26 09:16:44 +02:00
eventpoll.c	fs: add new vfs_poll and file_can_poll helpers	2018-05-26 09:16:44 +02:00
exec.c	umh: introduce fork_usermode_blob() helper	2018-05-23 13:23:39 -04:00
fcntl.c	mm: restructure memfd code	2018-06-07 17:34:35 -07:00
fhandle.c	vfs: Copy struct mount.mnt_id to userspace using put_user()	2018-01-15 12:07:51 -08:00
file.c	fs: add ksys_close() wrapper; remove in-kernel calls to sys_close()	2018-04-02 20:16:00 +02:00
file_table.c	…
filesystems.c	proc: introduce proc_create_single{,_data}	2018-05-16 07:23:35 +02:00
fs-writeback.c	bdi: Fix oops in wb_workfn()	2018-05-03 16:11:37 -06:00
fs_pin.c	…
fs_struct.c	…
inode.c	overlayfs fixes for 4.18	2018-06-07 08:53:50 -07:00
internal.h	Revert "fs: fold open_check_o_direct into do_dentry_open"	2018-06-03 10:58:23 -07:00
ioctl.c	fs: Allow CAP_SYS_ADMIN in s_user_ns to freeze and thaw filesystems	2018-05-24 12:04:28 -05:00
iomap.c	fs: use ->is_partially_uptodate in page_cache_seek_hole_data	2018-06-01 18:37:33 -07:00
libfs.c	fs, dax: prepare for dax-specific address_space_operations	2018-03-30 11:34:55 -07:00
locks.c	proc: introduce proc_create_seq_private	2018-05-16 07:23:35 +02:00
mbcache.c	…
mount.h	…
mpage.c	…
namei.c	Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2018-06-04 15:21:19 -07:00
namespace.c	fs: Allow superblock owner to access do_remount_sb()	2018-05-24 12:02:25 -05:00
no-block.c	…
nsfs.c	net: Export open_related_ns()	2018-02-15 15:34:42 -05:00
open.c	Revert "fs: fold open_check_o_direct into do_dentry_open"	2018-06-03 10:58:23 -07:00
pipe.c	pipe: convert to ->poll_mask	2018-05-26 09:16:44 +02:00
pnode.c	…
pnode.h	…
posix_acl.c	…
proc_namespace.c	vfs: do bulk POLL* -> EPOLL* replacement	2018-02-11 14:34:03 -08:00
read_write.c	fs: avoid fdput() after failed fdget() in vfs_dedupe_file_range()	2018-04-15 23:36:26 -04:00
readdir.c	fs: add ksys_getdents64() helper; remove in-kernel calls to sys_getdents64()	2018-04-02 20:16:02 +02:00
select.c	fs: introduce new ->get_poll_head and ->poll_mask methods	2018-05-26 09:16:44 +02:00
seq_file.c	proc: fix smaps and meminfo alignment	2018-05-25 18:12:11 -07:00
signalfd.c	signal: Extend siginfo_layout with SIL_FAULT_{MCEERR|BNDERR|PKUERR}	2018-04-26 19:51:14 -05:00
splice.c	fs: add do_vmsplice() helper; remove in-kernel call to syscall	2018-04-02 20:15:40 +02:00
stack.c	…
stat.c	fs: add do_readlinkat() helper; remove internal call to sys_readlinkat()	2018-04-02 20:15:34 +02:00
statfs.c	…
super.c	Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2018-06-04 10:14:28 -07:00
sync.c	Changes for this release:	2018-04-04 12:44:02 -07:00
timerfd.c	timerfd: convert to ->poll_mask	2018-05-26 09:16:44 +02:00
userfaultfd.c	userfaultfd: prevent non-cooperative events vs mcopy_atomic races	2018-06-07 17:34:38 -07:00
utimes.c	fs: add do_compat_futimesat() helper; remove in-kernel call to compat syscall	2018-04-02 20:15:44 +02:00
xattr.c	vfs: delete unnecessary assignment in vfs_listxattr	2018-05-29 13:22:41 -04:00