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a07279c9a8
linux-next/fs
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Jann Horn a07279c9a8 binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 
In both binfmt_elf and binfmt_elf_fdpic, use a new helper
dump_vma_snapshot() to take a snapshot of the VMA list (including the gate
VMA, if we have one) while protected by the mmap_lock, and then use that
snapshot instead of walking the VMA list without locking.

An alternative approach would be to keep the mmap_lock held across the
entire core dumping operation; however, keeping the mmap_lock locked while
we may be blocked for an unbounded amount of time (e.g.  because we're
dumping to a FUSE filesystem or so) isn't really optimal; the mmap_lock
blocks things like the ->release handler of userfaultfd, and we don't
really want critical system daemons to grind to a halt just because
someone "gifted" them SCM_RIGHTS to an eternally-locked userfaultfd, or
something like that.

Since both the normal ELF code and the FDPIC ELF code need this
functionality (and if any other binfmt wants to add coredump support in
the future, they'd probably need it, too), implement this with a common
helper in fs/coredump.c.

A downside of this approach is that we now need a bigger amount of kernel
memory per userspace VMA in the normal ELF case, and that we need O(n)
kernel memory in the FDPIC ELF case at all; but 40 bytes per VMA shouldn't
be terribly bad.

There currently is a data race between stack expansion and anything that
reads ->vm_start or ->vm_end under the mmap_lock held in read mode; to
mitigate that for core dumping, take the mmap_lock in write mode when
taking a snapshot of the VMA hierarchy.  (If we only took the mmap_lock in
read mode, we could end up with a corrupted core dump if someone does
get_user_pages_remote() concurrently.  Not really a major problem, but
taking the mmap_lock either way works here, so we might as well avoid the
issue.) (This doesn't do anything about the existing data races with stack
expansion in other mm code.)

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20200827114932.3572699-6-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16 11:11:21 -07:00
..
9p bdi: replace BDI_CAP_NO_{WRITEBACK,ACCT_DIRTY} with a single flag 2020-09-24 13:43:39 -06:00
adfs treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
affs affs: fix basic permission bits to actually work 2020-08-31 12:20:31 +02:00
afs block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
autofs autofs: use __kernel_write() for the autofs pipe writing 2020-09-29 17:18:34 -07:00
befs block: move struct block_device to blk_types.h 2020-06-24 09:16:02 -06:00
bfs
btrfs block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
cachefiles cachefiles: switch to kernel_write 2020-07-08 08:27:56 +02:00
ceph We have an inode number handling change, prompted by s390x which is 2020-08-28 10:33:04 -07:00
cifs cifs: Fix incomplete memory allocation on setxattr path 2020-10-10 15:52:54 -07:00
coda
configfs fs: configfs: delete repeated words in comments 2020-10-16 11:11:19 -07:00
cramfs
crypto fscrypt: export fscrypt_d_revalidate() 2020-09-28 14:44:51 -07:00
debugfs debugfs: Fix module state check condition 2020-09-04 18:12:52 +02:00
devpts
dlm dlm for 5.10 2020-10-13 08:59:39 -07:00
ecryptfs mm, treewide: rename kzfree() to kfree_sensitive() 2020-08-07 11:33:22 -07:00
efivarfs efivarfs: Replace invalid slashes with exclamation marks in dentries. 2020-09-25 23:29:04 +02:00
efs block: move struct block_device to blk_types.h 2020-06-24 09:16:02 -06:00
erofs erofs: remove unnecessary enum entries 2020-10-09 10:37:42 +08:00
exfat exfat: fix use of uninitialized spinlock on error path 2020-10-07 14:27:13 +09:00
exportfs
ext2 \n 2020-10-15 14:56:15 -07:00
ext4 mm/readahead: make page_cache_ra_unbounded take a readahead_control 2020-10-16 11:11:16 -07:00
f2fs mm/readahead: make page_cache_ra_unbounded take a readahead_control 2020-10-16 11:11:16 -07:00
fat fat: fix fat_ra_init() for data clusters == 0 2020-08-12 10:58:01 -07:00
freevxfs
fscache Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2020-06-03 16:27:18 -07:00
fuse block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
gfs2 Fix memory leak on filesystem withdraw 2020-08-28 10:41:00 -07:00
hfs block: move block-related definitions out of fs.h 2020-06-24 09:16:02 -06:00
hfsplus treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
hostfs
hpfs hpfs: fix warning due to superfluous semicolon 2020-06-06 10:08:17 -07:00
hugetlbfs hugetlbfs: prevent filesystem stacking of hugetlbfs 2020-08-12 10:57:56 -07:00
iomap iomap: Call inode_dio_end() before generic_write_sync() 2020-09-28 08:51:08 -07:00
isofs Remove uninitialized_var() macro for v5.9-rc1 2020-08-04 13:49:43 -07:00
jbd2 jbd2: clean up checksum verification in do_one_pass() 2020-08-19 12:04:35 -04:00
jffs2 treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
jfs fs: Introduce i_blocks_per_page 2020-09-21 08:59:26 -07:00
kernfs fsnotify: pass dir and inode arguments to fsnotify() 2020-07-27 23:15:48 +02:00
lockd
minix fs/minix: remove expected error message in block_to_path() 2020-08-12 10:58:00 -07:00
nfs block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
nfs_common treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
nfsd block: add a bdev_is_partition helper 2020-09-25 08:18:57 -06:00
nilfs2 treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
nls treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
notify treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
ntfs ntfs: add check for mft record size in superblock 2020-10-13 18:38:27 -07:00
ocfs2 ocfs2: fix potential soft lockup during fstrim 2020-10-13 18:38:27 -07:00
omfs treewide: Remove uninitialized_var() usage 2020-07-16 12:35:15 -07:00
openpromfs
orangefs orangefs: remove unnecessary assignment to variable ret 2020-08-04 15:01:58 -04:00
overlayfs Remove uninitialized_var() macro for v5.9-rc1 2020-08-04 13:49:43 -07:00
proc mm, oom_adj: don't loop through tasks in __set_oom_adj when not necessary 2020-10-13 18:38:35 -07:00
pstore treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
qnx4
qnx6 fs: convert mpage_readpages to mpage_readahead 2020-06-02 10:59:07 -07:00
quota \n 2020-10-15 14:56:15 -07:00
ramfs
reiserfs reiserfs: Fix oops during mount 2020-10-01 11:15:31 +02:00
romfs romfs: fix uninitialized memory leak in romfs_dev_read() 2020-08-21 09:52:53 -07:00
squashfs squashfs: avoid bio_alloc() failure with 1Mbyte blocks 2020-08-21 09:52:53 -07:00
sysfs sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-10-02 12:02:30 +02:00
sysv
tracefs
ubifs block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
udf udf: Limit sparing table size 2020-09-29 17:21:54 +02:00
ufs treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
unicode
vboxsf Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2020-10-15 15:11:56 -07:00
verity fs-verity: use smp_load_acquire() for ->i_verity_info 2020-07-21 16:02:41 -07:00
xfs New code for 5.10: 2020-10-14 14:06:06 -07:00
zonefs zonefs: add zone-capacity support 2020-08-11 17:42:24 +09:00
aio.c Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-12 16:35:51 -07:00
anon_inodes.c
attr.c
bad_inode.c fs: move the fiemap definitions out of fs.h 2020-06-03 23:16:55 -04:00
binfmt_aout.c
binfmt_elf_fdpic.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
binfmt_elf.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
binfmt_em86.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_flat.c binfmt_flat: revert "binfmt_flat: don't offset the data start" 2020-08-24 08:49:13 +10:00
binfmt_misc.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_script.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
block_dev.c block: add a bdget_part helper 2020-10-05 10:38:33 -06:00
buffer.c fs: Don't invalidate page buffers in block_write_full_page() 2020-09-07 10:23:07 -06:00
char_dev.c vfs: allow unprivileged whiteout creation 2020-05-14 16:44:23 +02:00
compat_binfmt_elf.c Split the old READ_IMPLIES_EXEC workaround from executable PT_GNU_STACK 2020-06-05 13:45:21 -07:00
coredump.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-14 14:54:45 -07:00
dax.c iomap: Change calling convention for zeroing 2020-09-21 08:59:27 -07:00
dcache.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
dcookies.c
direct-io.c \n 2020-10-15 15:03:10 -07:00
drop_caches.c
eventfd.c
eventpoll.c ep_create_wakeup_source(): dentry name can change under you... 2020-09-24 19:41:58 -04:00
exec.c Char/Misc driver patches for 5.10-rc1 2020-10-15 10:01:51 -07:00
fcntl.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
fhandle.c
file_table.c Revert "fs: Do not check if there is a fsnotify watcher on pseudo inodes" 2020-06-29 09:40:55 -07:00
file.c io_uring: don't rely on weak ->files references 2020-09-30 20:32:32 -06:00
filesystems.c
fs_context.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
fs_parser.c fs_parse: mark fs_param_bad_value() as static 2020-10-13 18:38:27 -07:00
fs_pin.c
fs_struct.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
fs_types.c
fs-writeback.c block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
fsopen.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
init.c init: add an init_dup helper 2020-08-04 21:02:38 -04:00
inode.c fs: add a filesystem flag for THPs 2020-10-16 11:11:15 -07:00
internal.h fs: remove compat_sys_mount 2020-09-22 23:45:57 -04:00
io_uring.c io_uring-5.10-2020-10-12 2020-10-13 12:36:21 -07:00
io-wq.c io-wq: kill unused IO_WORKER_F_EXITING 2020-09-30 20:32:34 -06:00
io-wq.h io_uring: add blkcg accounting to offloaded operations 2020-09-30 20:32:34 -06:00
ioctl.c fs: remove ksys_ioctl 2020-07-31 08:16:01 +02:00
Kconfig tmpfs: support 64-bit inums per-sb 2020-08-07 11:33:24 -07:00
Kconfig.binfmt treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
kernel_read_file.c fs/kernel_file_read: Add "offset" arg for partial reads 2020-10-05 13:37:04 +02:00
libfs.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
locks.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
Makefile Char/Misc driver patches for 5.10-rc1 2020-10-15 10:01:51 -07:00
mbcache.c
mount.h proc/mounts: add cursor 2020-05-14 16:44:24 +02:00
mpage.c fs: convert mpage_readpages to mpage_readahead 2020-06-02 10:59:07 -07:00
namei.c fs: remove the unused SB_I_MULTIROOT flag 2020-09-24 13:43:38 -06:00
namespace.c Merge branch 'compat.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-12 16:44:57 -07:00
no-block.c
nsfs.c nsproxy: attach to namespaces via pidfds 2020-05-13 11:41:22 +02:00
open.c exec: move S_ISREG() check earlier 2020-08-12 10:58:01 -07:00
pipe.c Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-11 11:11:35 -07:00
pnode.c
pnode.h
posix_acl.c vfs: clean up posix_acl_permission() logic aroudn MAY_NOT_BLOCK 2020-06-08 11:04:19 -07:00
proc_namespace.c Merge branch 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-06-04 13:54:34 -07:00
read_write.c Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-12 16:35:51 -07:00
readdir.c fs: remove ksys_getdents64 2020-07-31 08:16:00 +02:00
select.c pselect6() and friends: take handling the combined 6th/7th args into helper 2020-05-29 19:10:42 -04:00
seq_file.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
signalfd.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
splice.c Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-12 16:35:51 -07:00
stack.c
stat.c New code for 5.8: 2020-06-02 19:45:12 -07:00
statfs.c
super.c bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag 2020-09-24 13:43:39 -06:00
sync.c overlayfs update for 5.8 2020-06-09 15:40:50 -07:00
timerfd.c
userfaultfd.c A set of locking fixes and updates: 2020-08-10 19:07:44 -07:00
utimes.c fs: expose utimes_common 2020-07-31 08:16:01 +02:00
xattr.c fs/xattr.c: fix kernel-doc warnings for setxattr & removexattr 2020-10-13 18:38:27 -07:00