leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity
ae62fbe299
linux/fs
History
David Hildenbrand 25bc5b0de9 proc/vmcore: don't fake reading zeroes on surprise vmcore_cb unregistration 
In commit cc5f2704c9 ("proc/vmcore: convert oldmem_pfn_is_ram callback
to more generic vmcore callbacks"), we added detection of surprise
vmcore_cb unregistration after the vmcore was already opened.  Once
detected, we warn the user and simulate reading zeroes from that point
on when accessing the vmcore.

The basic reason was that unexpected unregistration, for example, by
manually unbinding a driver from a device after opening the vmcore, is
not supported and could result in reading oldmem the vmcore_cb would
have actually prohibited while registered.  However, something like that
can similarly be trigger by a user that's really looking for trouble
simply by unbinding the relevant driver before opening the vmcore -- or
by disallowing loading the driver in the first place.  So it's actually
of limited help.

Currently, unregistration can only be triggered via virtio-mem when
manually unbinding the driver from the device inside the VM; there is no
way to trigger it from the hypervisor, as hypervisors don't allow for
unplugging virtio-mem devices -- ripping out system RAM from a VM
without coordination with the guest is usually not a good idea.

The important part is that unbinding the driver and unregistering the
vmcore_cb while concurrently reading the vmcore won't crash the system,
and that is handled by the rwsem.

To make the mechanism more future proof, let's remove the "read zero"
part, but leave the warning in place.  For example, we could have a
future driver (like virtio-balloon) that will contact the hypervisor to
figure out if we already populated a page for a given PFN.
Hotunplugging such a device and consequently unregistering the vmcore_cb
could be triggered from the hypervisor without harming the system even
while kdump is running.  In that case, we don't want to silently end up
with a vmcore that contains wrong data, because the user inside the VM
might be unaware of the hypervisor action and might easily miss the
warning in the log.

Link: https://lkml.kernel.org/r/20211111192243.22002-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Philipp Rudo <prudo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-20 08:52:52 +02:00
..
9p netfs, 9p, afs, ceph: Use folios 2021-11-10 21:16:56 +00:00
adfs mm: require ->set_page_dirty to be explicitly wired up 2021-06-29 10:53:48 -07:00
affs affs: use bdev_nr_sectors instead of open coding it 2021-10-18 14:43:22 -06:00
afs afs: Fix mmap 2021-12-16 09:10:13 -08:00
autofs autofs: fix wait name hash calculation in autofs_wait() 2021-10-20 21:09:02 -04:00
befs isystem: ship and use stdarg.h 2021-08-19 09:02:55 +09:00
bfs mm: require ->set_page_dirty to be explicitly wired up 2021-06-29 10:53:48 -07:00
btrfs for-5.16-rc5-tag 2021-12-17 13:50:58 -08:00
cachefiles for-5.16/ki_complete-2021-10-29 2021-11-01 10:17:11 -07:00
ceph ceph: fix up non-directory creation in SGID directories 2021-12-01 17:08:27 +01:00
cifs cifs: sanitize multiple delimiters in prepath 2021-12-17 19:16:49 -06:00
coda coda: bump module version to 7.2 2021-11-09 10:02:51 -08:00
configfs configfs: fix a race in configfs_lookup() 2021-08-25 07:58:49 +02:00
cramfs cramfs: use bdev_nr_bytes instead of open coding it 2021-10-18 14:43:22 -06:00
crypto fscrypt: improve a few comments 2021-10-25 19:11:50 -07:00
debugfs debugfs: debugfs_create_file_size(): use IS_ERR to check for error 2021-09-21 09:09:06 +02:00
devpts
dlm fs: dlm: avoid comms shutdown delay in release_lockspace 2021-09-01 11:29:14 -05:00
ecryptfs mm: require ->set_page_dirty to be explicitly wired up 2021-06-29 10:53:48 -07:00
efivarfs efivars: convert to fileattr 2021-04-12 15:04:29 +02:00
efs
erofs erofs: fix deadlock when shrink erofs slab 2021-11-23 14:58:16 +08:00
exfat exfat: fix incorrect loading of i_blocks for large files 2021-11-01 07:49:21 +09:00
exportfs
ext2 ext2: fix sleeping in atomic bugs on error 2021-09-22 13:05:23 +02:00
ext4 Only bug fixes and cleanups for ext4 this merge window. Of note are 2021-11-10 17:05:37 -08:00
f2fs Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
fat for-5.16/inode-sync-2021-10-29 2021-11-01 10:25:27 -07:00
freevxfs
fscache fscache: Remove an unused static variable 2021-10-04 22:13:12 +01:00
fuse fuse: release pipe buf after last use 2021-11-25 14:05:18 +01:00
gfs2 gfs2: gfs2_create_inode rework 2021-12-02 12:41:10 +01:00
hfs Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
hfsplus Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
hostfs hostfs: support splice_write 2021-08-26 22:28:02 +02:00
hpfs treewide: Replace open-coded flex arrays in unions 2021-10-18 12:28:53 -07:00
hugetlbfs mm,hugetlb: remove mlock ulimit for SHM_HUGETLB 2021-11-09 10:02:48 -08:00
iomap iomap: iomap_read_inline_data cleanup 2021-11-24 10:15:47 -08:00
isofs isofs: Fix out of bound access for corrupted isofs image 2021-10-19 12:51:02 +02:00
jbd2 jbd2: add sparse annotations for add_transaction_credits() 2021-08-30 23:36:50 -04:00
jffs2 vfs: add rcu argument to ->get_acl() callback 2021-08-18 22:08:24 +02:00
jfs Just one JFS patch 2021-11-03 09:23:25 -07:00
kernfs Merge 5.15-rc6 into driver-core-next 2021-10-18 09:43:37 +02:00
ksmbd ksmbd: disable SMB2_GLOBAL_CAP_ENCRYPTION for SMB 3.1.1 2021-12-17 19:19:45 -06:00
lockd A slow cycle for nfsd: mainly cleanup, including Neil's patch dropping 2021-11-10 16:45:54 -08:00
minix mm: require ->set_page_dirty to be explicitly wired up 2021-06-29 10:53:48 -07:00
netfs netfs: fix parameter of cleanup() 2021-12-07 15:47:09 +00:00
nfs NFS client bugfixes for Linux 5.16 2021-11-27 10:33:55 -08:00
nfs_common nfs: Fix kerneldoc warning shown up by W=1 2021-10-04 22:02:17 +01:00
nfsd NFSD: Fix READDIR buffer overflow 2021-12-18 17:11:06 -05:00
nilfs2 Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
nls
notify fanotify: Allow users to request FAN_FS_ERROR events 2021-10-27 12:53:45 +02:00
ntfs fs: ntfs: Limit NTFS_RW to page sizes smaller than 64k 2021-11-27 14:34:41 -08:00
ntfs3 gfs2: Fix mmap + page fault deadlocks 2021-11-02 12:25:03 -07:00
ocfs2 Merge branch 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2021-11-10 16:15:54 -08:00
omfs mm: require ->set_page_dirty to be explicitly wired up 2021-06-29 10:53:48 -07:00
openpromfs
orangefs orangefs: three fixes from other folks... 2021-11-09 10:34:06 -08:00
overlayfs overlayfs update for 5.16 2021-11-09 10:51:12 -08:00
proc proc/vmcore: don't fake reading zeroes on surprise vmcore_cb unregistration 2022-01-20 08:52:52 +02:00
pstore pstore/blk: Use "%lu" to format unsigned long 2021-11-21 09:44:19 -08:00
qnx4 qnx4: work around gcc false positive warning bug 2021-09-21 08:36:48 -07:00
qnx6
quota \n 2021-11-06 16:40:48 -07:00
ramfs Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
reiserfs \n 2021-11-06 16:40:48 -07:00
romfs
smbfs_common cifs: Fix crash on unload of cifs_arc4.ko 2021-12-07 22:38:03 -06:00
squashfs lib: zstd: Add kernel-specific API 2021-11-08 16:55:21 -08:00
sysfs fs/sysfs/dir.c: replace S_IRWXU|S_IRUGO|S_IXUGO with 0755 sysfs_create_dir_ns() 2021-10-05 16:35:05 +02:00
sysv sysv: use BUILD_BUG_ON instead of runtime check 2021-11-09 10:02:52 -08:00
tracefs tracefs: Set all files to the same group ownership as the mount option 2021-12-08 08:06:40 -05:00
ubifs fscrypt: remove fscrypt_operations::max_namelen 2021-09-20 19:32:33 -07:00
udf udf: Fix crash after seekdir 2021-11-09 12:53:58 +01:00
ufs isystem: ship and use stdarg.h 2021-08-19 09:02:55 +09:00
unicode .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
vboxsf vboxfs: fix broken legacy mount signature checking 2021-09-27 11:26:21 -07:00
verity fs-verity: fix signed integer overflow with i_size near S64_MAX 2021-09-22 10:56:34 -07:00
xfs xfs: map unwritten blocks in XFS_IOC_{ALLOC,FREE}SP just like fallocate 2021-12-22 14:19:18 -08:00
zonefs zonefs: add MODULE_ALIAS_FS 2021-12-17 16:56:35 +09:00
aio.c aio: Fix incorrect usage of eventfd_signal_allowed() 2021-12-09 10:52:55 -08:00
anon_inodes.c fs: add anon_inode_getfile_secure() similar to anon_inode_getfd_secure() 2021-09-19 22:35:37 -04:00
attr.c fs: handle circular mappings correctly 2021-11-17 09:26:09 +01:00
bad_inode.c vfs: add rcu argument to ->get_acl() callback 2021-08-18 22:08:24 +02:00
binfmt_aout.c binfmt: a.out: Fix bogus semicolon 2021-09-05 10:15:05 -07:00
binfmt_elf_fdpic.c coredump: Limit coredumps to a single thread group 2021-10-08 12:06:02 -05:00
binfmt_elf.c Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
binfmt_flat.c binfmt: remove in-tree usage of MAP_EXECUTABLE 2021-06-29 10:53:50 -07:00
binfmt_misc.c
binfmt_script.c
buffer.c fs: simplify init_page_buffers 2021-10-18 14:43:22 -06:00
char_dev.c
compat_binfmt_elf.c
coredump.c coredump: Limit coredumps to a single thread group 2021-10-08 12:06:02 -05:00
d_path.c d_path: fix Kernel doc validator complaining 2021-11-06 13:30:32 -07:00
dax.c New code for 5.15: 2021-08-31 11:13:35 -07:00
dcache.c useful constants: struct qstr for ".." 2021-04-15 22:36:45 -04:00
direct-io.c fs: get rid of the res2 iocb->ki_complete argument 2021-10-25 10:36:24 -06:00
drop_caches.c fs: drop_caches: fix skipping over shadow cache inodes 2021-09-03 09:58:10 -07:00
eventfd.c eventfd: Export eventfd_wake_count to modules 2021-09-06 07:20:56 -04:00
eventpoll.c ARM development updates for 5.15: 2021-09-09 13:25:49 -07:00
exec.c Merge branch 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2021-11-10 16:15:54 -08:00
fcntl.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
fhandle.c switch file_open_root() to struct path 2021-04-07 13:56:43 -04:00
file_table.c
file.c fget: clarify and improve __fget_files() implementation 2021-12-13 10:55:30 -08:00
filesystems.c fs: simplify get_filesystem_list / get_all_fs_names 2021-08-23 01:25:40 -04:00
fs_context.c memcg: charge fs_context and legacy_fs_context 2021-09-03 09:58:12 -07:00
fs_parser.c namei: Standardize callers of filename_lookup() 2021-09-07 16:07:47 -04:00
fs_pin.c
fs_struct.c
fs_types.c
fs-writeback.c Various hardening fixes and cleanups for 5.16-rc1 2021-11-01 17:29:10 -07:00
fsopen.c
init.c
inode.c fs: Remove FS_THP_SUPPORT 2021-11-17 10:36:35 -05:00
internal.h Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
io_uring.c io_uring: zero iocb->ki_pos for stream file types 2021-12-22 20:34:32 -07:00
io-wq.c io-wq: drop wqe lock before creating new worker 2021-12-13 09:04:01 -07:00
io-wq.h io_uring: optimise INIT_WQ_LIST 2021-10-19 05:49:54 -06:00
ioctl.c New code for 5.15: 2021-08-31 11:06:32 -07:00
Kconfig 4 cifs/smb3 fixes, one for DFS reconnect, and one to begin creating common headers for server and client and the other two to rename the cifs_common directory to smbfs_common to be more consistent ie change use of the name cifs to smb which is more accurate 2021-09-12 10:10:21 -07:00
Kconfig.binfmt binfmt: remove support for em86 (alpha only) 2021-07-25 22:33:03 -07:00
kernel_read_file.c vfs: check fd has read access in kernel_read_file_from_fd() 2021-10-18 20:22:03 -10:00
libfs.c libfs: Support RENAME_EXCHANGE in simple_rename() 2021-11-03 15:43:08 +01:00
locks.c locks: remove changelog comments 2021-10-19 14:11:39 -04:00
Makefile 4 cifs/smb3 fixes, one for DFS reconnect, and one to begin creating common headers for server and client and the other two to rename the cifs_common directory to smbfs_common to be more consistent ie change use of the name cifs to smb which is more accurate 2021-09-12 10:10:21 -07:00
mbcache.c
mount.h
mpage.c
namei.c File locking changes for v5.16 2021-11-01 09:06:53 -07:00
namespace.c fs/mount_setattr: always cleanup mount_kattr 2021-12-30 15:12:13 -08:00
no-block.c
nsfs.c
open.c Merge branch 'akpm' (patches from Andrew) 2021-11-06 14:08:17 -07:00
pipe.c Revert "mm/gup: remove try_get_page(), call try_get_compound_head() directly" 2021-09-07 11:03:45 -07:00
pnode.c
pnode.h
posix_acl.c fs/posix_acl.c: avoid -Wempty-body warning 2021-11-06 13:30:32 -07:00
proc_namespace.c
read_write.c fs: remove leftover comments from mandatory locking removal 2021-10-26 12:20:50 -04:00
readdir.c readdir: make sure to verify directory entry for legacy interfaces too 2021-04-17 11:39:49 -07:00
remap_range.c fs: remove mandatory file locking support 2021-08-23 06:15:36 -04:00
select.c Revert "memcg: enable accounting for pollfd and select bits arrays" 2021-09-07 11:26:23 -07:00
seq_file.c seq_file: move seq_escape() to a header 2021-11-09 10:02:52 -08:00
signalfd.c signalfd: use wake_up_pollfree() 2021-12-09 10:49:56 -08:00
splice.c
stack.c
stat.c fs: add generic helper for filling statx attribute flags 2021-08-17 11:47:43 +02:00
statfs.c
super.c fs: explicitly unregister per-superblock BDIs 2021-11-06 13:30:34 -07:00
sync.c block: simplify the block device syncing code 2021-10-22 08:36:55 -06:00
timerfd.c timerfd: Provide timerfd_resume() 2021-08-10 17:57:22 +02:00
userfaultfd.c userfaultfd: fix a race between writeprotect and exit_mmap() 2021-10-18 20:22:02 -10:00
utimes.c
xattr.c xattr: fix kernel-doc for mnt_userns and vfs xattr helpers 2021-03-23 11:20:26 +01:00