linux-stable.git/fs/configfs, branch linux-5.11.y

configfs: fix a use-after-free in __configfs_open_file

2021-03-17T16:11:42+00:00

[ Upstream commit 14fbbc8297728e880070f7b077b3301a8c698ef9 ]

Commit b0841eefd969 ("configfs: provide exclusion between IO and removals")
uses ->frag_dead to mark the fragment state, thus no bothering with extra
refcount on config_item when opening a file. The configfs_get_config_item
was removed in __configfs_open_file, but not with config_item_put. So the
refcount on config_item will lost its balance, causing use-after-free
issues in some occasions like this:

Test:
1. Mount configfs on /config with read-only items:
drwxrwx--- 289 root   root            0 2021-04-01 11:55 /config
drwxr-xr-x   2 root   root            0 2021-04-01 11:54 /config/a
--w--w--w-   1 root   root         4096 2021-04-01 11:53 /config/a/1.txt
......

2. Then run:
for file in /config
do
echo $file
grep -R 'key' $file
done

3. __configfs_open_file will be called in parallel, the first one
got called will do:
if (file->f_mode & FMODE_READ) {
	if (!(inode->i_mode & S_IRUGO))
		goto out_put_module;
			config_item_put(buffer->item);
				kref_put()
					package_details_release()
						kfree()

the other one will run into use-after-free issues like this:
BUG: KASAN: use-after-free in __configfs_open_file+0x1bc/0x3b0
Read of size 8 at addr fffffff155f02480 by task grep/13096
CPU: 0 PID: 13096 Comm: grep VIP: 00 Tainted: G        W       4.14.116-kasan #1
TGID: 13096 Comm: grep
Call trace:
dump_stack+0x118/0x160
kasan_report+0x22c/0x294
__asan_load8+0x80/0x88
__configfs_open_file+0x1bc/0x3b0
configfs_open_file+0x28/0x34
do_dentry_open+0x2cc/0x5c0
vfs_open+0x80/0xe0
path_openat+0xd8c/0x2988
do_filp_open+0x1c4/0x2fc
do_sys_open+0x23c/0x404
SyS_openat+0x38/0x48

Allocated by task 2138:
kasan_kmalloc+0xe0/0x1ac
kmem_cache_alloc_trace+0x334/0x394
packages_make_item+0x4c/0x180
configfs_mkdir+0x358/0x740
vfs_mkdir2+0x1bc/0x2e8
SyS_mkdirat+0x154/0x23c
el0_svc_naked+0x34/0x38

Freed by task 13096:
kasan_slab_free+0xb8/0x194
kfree+0x13c/0x910
package_details_release+0x524/0x56c
kref_put+0xc4/0x104
config_item_put+0x24/0x34
__configfs_open_file+0x35c/0x3b0
configfs_open_file+0x28/0x34
do_dentry_open+0x2cc/0x5c0
vfs_open+0x80/0xe0
path_openat+0xd8c/0x2988
do_filp_open+0x1c4/0x2fc
do_sys_open+0x23c/0x404
SyS_openat+0x38/0x48
el0_svc_naked+0x34/0x38

To fix this issue, remove the config_item_put in
__configfs_open_file to balance the refcount of config_item.

Fixes: b0841eefd969 ("configfs: provide exclusion between IO and removals")
Signed-off-by: Daiyue Zhang 
Signed-off-by: Yi Chen 
Signed-off-by: Ge Qiu 
Reviewed-by: Chao Yu 
Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Sasha Levin

configfs: fix kernel-doc markup issue

2020-11-14T09:22:45+00:00

Add explanation for 'frag' parameter to avoid kernel-doc issue:
fs/configfs/dir.c:277: warning: Function parameter or member 'frag' not
described in 'configfs_create_dir'

Signed-off-by: Alex Shi 
Cc: Joel Becker 
Cc: Christoph Hellwig 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Christoph Hellwig

fs: configfs: delete repeated words in comments

2020-10-16T18:11:19+00:00

Drop duplicated words {the, that} in comments.

Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Cc: Joel Becker 
Cc: Christoph Hellwig 
Link: https://lkml.kernel.org/r/20200811021826.25032-1-rdunlap@infradead.org
Signed-off-by: Linus Torvalds

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59+00:00

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva

Merge tag 'docs-5.8' of git://git.lwn.net/linux

2020-06-01T22:45:27+00:00

Pull documentation updates from Jonathan Corbet:
 "A fair amount of stuff this time around, dominated by yet another
  massive set from Mauro toward the completion of the RST conversion. I
  *really* hope we are getting close to the end of this. Meanwhile,
  those patches reach pretty far afield to update document references
  around the tree; there should be no actual code changes there. There
  will be, alas, more of the usual trivial merge conflicts.

  Beyond that we have more translations, improvements to the sphinx
  scripting, a number of additions to the sysctl documentation, and lots
  of fixes"

* tag 'docs-5.8' of git://git.lwn.net/linux: (130 commits)
  Documentation: fixes to the maintainer-entry-profile template
  zswap: docs/vm: Fix typo accept_threshold_percent in zswap.rst
  tracing: Fix events.rst section numbering
  docs: acpi: fix old http link and improve document format
  docs: filesystems: add info about efivars content
  Documentation: LSM: Correct the basic LSM description
  mailmap: change email for Ricardo Ribalda
  docs: sysctl/kernel: document unaligned controls
  Documentation: admin-guide: update bug-hunting.rst
  docs: sysctl/kernel: document ngroups_max
  nvdimm: fixes to maintainter-entry-profile
  Documentation/features: Correct RISC-V kprobes support entry
  Documentation/features: Refresh the arch support status files
  Revert "docs: sysctl/kernel: document ngroups_max"
  docs: move locking-specific documents to locking/
  docs: move digsig docs to the security book
  docs: move the kref doc into the core-api book
  docs: add IRQ documentation at the core-api book
  docs: debugging-via-ohci1394.txt: add it to the core-api book
  docs: fix references for ipmi.rst file
  ...

docs: filesystems: convert configfs.txt to ReST

2020-05-05T15:23:25+00:00

- Add a SPDX header;
- Adjust document and section titles;
- Use copyright symbol;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to filesystems/index.rst.

Also, as this file is alone on its own dir, and it doesn't
seem too likely that other documents will follow it, let's
move it to the filesystems/ root documentation dir.

Signed-off-by: Mauro Carvalho Chehab 
Link: https://lore.kernel.org/r/c2424ec2ad4d735751434ff7f52144c44aa02d5a.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet

configfs: fix config_item refcnt leak in configfs_rmdir()

2020-04-27T06:17:10+00:00

configfs_rmdir() invokes configfs_get_config_item(), which returns a
reference of the specified config_item object to "parent_item" with
increased refcnt.

When configfs_rmdir() returns, local variable "parent_item" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling path of
configfs_rmdir(). When down_write_killable() fails, the function forgets
to decrease the refcnt increased by configfs_get_config_item(), causing
a refcnt leak.

Fix this issue by calling config_item_put() when down_write_killable()
fails.

Signed-off-by: Xiyu Yang 
Signed-off-by: Xin Tan 
Signed-off-by: Christoph Hellwig

utimes: Clamp the timestamps in notify_change()

2019-12-09T00:10:50+00:00

Push clamping timestamps into notify_change(), so in-kernel
callers like nfsd and overlayfs will get similar timestamp
set behavior as utimes.

AV: get rid of clamping in ->setattr() instances; we don't need
to bother with that there, with notify_change() doing normalization
in all cases now (it already did for implicit case, since current_time()
clamps).

Suggested-by: Miklos Szeredi 
Fixes: 42e729b9ddbb ("utimes: Clamp the timestamps before update")
Cc: stable@vger.kernel.org # v5.4
Cc: Deepa Dinamani 
Cc: Jeff Layton 
Signed-off-by: Amir Goldstein 
Signed-off-by: Al Viro

configfs: calculate the depth of parent item

2019-11-06T17:36:01+00:00

When create symbolic link, create_link should calculate the depth
of the parent item. However, both the first and second parameters
of configfs_get_target_path had been set to the target. Broken
symbolic link created.

$ targetcli ls /
o- / ............................................................. [...]
  o- backstores .................................................. [...]
  | o- block ...................................... [Storage Objects: 0]
  | o- fileio ..................................... [Storage Objects: 2]
  | | o- vdev0 .......... [/dev/ramdisk1 (16.0MiB) write-thru activated]
  | | | o- alua ....................................... [ALUA Groups: 1]
  | | |   o- default_tg_pt_gp ........... [ALUA state: Active/optimized]
  | | o- vdev1 .......... [/dev/ramdisk2 (16.0MiB) write-thru activated]
  | |   o- alua ....................................... [ALUA Groups: 1]
  | |     o- default_tg_pt_gp ........... [ALUA state: Active/optimized]
  | o- pscsi ...................................... [Storage Objects: 0]
  | o- ramdisk .................................... [Storage Objects: 0]
  o- iscsi ................................................ [Targets: 0]
  o- loopback ............................................. [Targets: 0]
  o- srpt ................................................. [Targets: 2]
  | o- ib.e89a8f91cb3200000000000000000000 ............... [no-gen-acls]
  | | o- acls ................................................ [ACLs: 2]
  | | | o- ib.e89a8f91cb3200000000000000000000 ........ [Mapped LUNs: 2]
  | | | | o- mapped_lun0 ............................. [BROKEN LUN LINK]
  | | | | o- mapped_lun1 ............................. [BROKEN LUN LINK]
  | | | o- ib.e89a8f91cb3300000000000000000000 ........ [Mapped LUNs: 2]
  | | |   o- mapped_lun0 ............................. [BROKEN LUN LINK]
  | | |   o- mapped_lun1 ............................. [BROKEN LUN LINK]
  | | o- luns ................................................ [LUNs: 2]
  | |   o- lun0 ...... [fileio/vdev0 (/dev/ramdisk1) (default_tg_pt_gp)]
  | |   o- lun1 ...... [fileio/vdev1 (/dev/ramdisk2) (default_tg_pt_gp)]
  | o- ib.e89a8f91cb3300000000000000000000 ............... [no-gen-acls]
  |   o- acls ................................................ [ACLs: 0]
  |   o- luns ................................................ [LUNs: 0]
  o- vhost ................................................ [Targets: 0]

Fixes: e9c03af21cc7 ("configfs: calculate the symlink target only once")
Signed-off-by: Honggang Li 
Signed-off-by: Christoph Hellwig

Merge tag 'configfs-for-5.4' of git://git.infradead.org/users/hch/configfs

2019-09-19T20:09:28+00:00

Pull configfs updates from Christoph Hellwig:

 - fix a symlink deadlock (Al Viro)

 - various cleanups (Al Viro, me)

* tag 'configfs-for-5.4' of git://git.infradead.org/users/hch/configfs:
  configfs: calculate the symlink target only once
  configfs: make configfs_create() return inode
  configfs: factor dirent removal into helpers
  configfs: fix a deadlock in configfs_symlink()