When do_resume calls dm_table_get_mode(new_map), the call is done without
holding any locks (it only holds a reference to the md). It may be
possible that another concurrent ioctl on the same device will swap table
after dm_swap_table and before dm_table_get_mode. In this case,
dm_table_get_mode(new_map) reads freed memory.
This race condition was triggered by syzbot.
This commit fixes the race by reading mode of the new table before
dm_swap_table. Note that new_map is also passed to dm_ima_need_measure,
but this function doesn't attempt to dereference it, so this call should
be safe.
Note that this is not a security bug because only root can trigger it and
the commonly used tools such as lvm or cryptsetup do not call the ioctls
concurrently, so that they can't trigger it acceidentally.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: syzbot+bdff1ecf726d2af66afd@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
struct dm_ioctl has seven bytes of trailing padding, so the smallest
buffer userspace is allowed to ask for, offsetof(struct dm_ioctl, data),
is seven bytes shorter than sizeof(struct dm_ioctl).
get_result_buffer() sets data_start to sizeof(struct dm_ioctl) without
looking at how big the buffer actually is. Ask for the minimum and
data_start ends up seven bytes past the end. Callers add it to
data_size, and ctl_ioctl() copies that much back to userspace:
BUG: KASAN: slab-out-of-bounds in _copy_to_user+0xad/0xd0
Read of size 312 at addr ffff8880169e4c00 by task repro-dm/140
ctl_ioctl+0x5e3/0xcb0
dm_ctl_ioctl+0x25/0x40
allocated 305-byte region [ffff8880169e4c00, ffff8880169e4d31)
A DM_LIST_DEVICES with data_size set to 305 is enough to hit it, and the
seven bytes that leak are whatever sat next to the allocation.
Clamp data_start to the buffer size.
Note that this is not a security bug because the out-of-bounds read can
only be triggered by root.
Reported-by: syzbot+48d935cf48a4a76be346@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=48d935cf48a4a76be346
Fixes: 76c072b48e ("dm ioctl: move compat code")
Cc: stable@vger.kernel.org
Signed-off-by: Palla Raghunath <raghunathpalla.0209@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Use designated initialisers for the _ioctls[] array and delete the
unused field that contained the array index.
Makes the code more robust against the order of the initialers.
Any uninitialised entries would be processed corretly.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Instead of doing a prescan to determine the length of buffer required,
checking the supplied buffer is big enough, and then doing a second
scan to fill the output buffer just do a single scan and detect when
the buffer is too short.
For additional safety only call strlen() once and use the
returned length for everything (incuding the copy).
Ensure than all the pad bytes between the entries are zero.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Instead of doing a prescan to determine the length of buffer required,
checking the supplied buffer is big enough, and then doing a second
scan to fill the output buffer just do a single scan and detect when
the buffer is too short.
This removes any problems that might occur if a 'target' is added
between the scans.
For additional safety only call strlen(tt->name) once and use the
returned length for everything (incuding the copy).
Ensure than all the pad bytes between the entries are zero.
Set param->data_size to the actual size of the data.
It was slightly large because ALIGN_MASK was added in instead of the size
being rounded up.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
nonseekable_open() never fails, so the error check is unnecessary.
Remove the dead error handling path.
Signed-off-by: Bui Duc Phuc <phucduc.bui@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
The condition "remaining <= 0" can never be true. The variable remaining
has type size_t, thus it can't be negative. It can't be zero because we
made sure earlier that "remaining > sizeof(struct dm_target_spec)" and
then we added "sizeof(struct dm_target_spec)" to "outptr" (this means
that we subtraceted "sizeof(struct dm_target_spec)" from "remaining").
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Assisted-by: Claude:claude-opus-4.6
sizeof(tt->version) is 12 bytes, but the code writes 16 bytes into the
output buffer - info->vers->version[0], info->vers->version[1],
info->vers->version[2] and info->vers->next. This can cause buffer
overflow.
Fix this buffer overflow by replacing "sizeof(tt->version)" with
"sizeof(struct dm_target_versions)".
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Assisted-by: Claude:claude-opus-4.6
Cc: stable@vger.kernel.org
If dm_resume fails, the kernel attempts to free table with
dm_table_destroy, but the table was already instantiated with
dm_swap_table. This commit skips the call to dm_table_destroy in this
case.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Assisted-by: Claude:claude-opus-4.6
Fixes: 6bbc923dfc ("dm: add support to directly boot to a mapped device")
Cc: stable@vger.kernel.org
When we send a message to a device that has no table, the return code was
not set. The code would return "2", which is not considered a valid return value.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
Now that two processes can't modify md->ima in
dm_ima_measure_on_device_clear() at the same time, there's no need to
track if an inactive table was actually removed. We might as well
clean it up unconditionally, on the off chance that a previous
ima measurement failed and left md->ima.inactive_table behind.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
the dm-ima code did not keep the dm_ima_measure_on_* functions from
running at the same time. This could lead to various errors. If two
processes were updating the device state, one could update the state
first, but the other could measure the state first, causing the the
current device state to appear incorrect. If a table load happened while
a device was resuming, the IMA measurement could report the wrong table
being active. And if two dm_ima_measure_on_* functions ran at the same
time, one of them could free data that the other was accessing, causing
a crash.
All the core dm functions that call a dm_ima_measure_on_* function
update the device state they want to measure under the _hash_lock,
except for do_resume(). But holding the _hash_lock is not a good way to
synchronize these functions. It's a global mutex, that is needed in many
dm operations, and the dm_ima_measure_* functions can sleep, blocking
any dm operation on any device that needs the _hash_lock.
To serialize and order the IMA measurement functions, the
dm_ima_measurements now has two counters, update_idx and measure_idx.
update_idx is incremented while holding the _hash_lock and saved, along
with the device name and uuid, in a dm_ima_context struct. Once the
_hash_lock is dropped, the dm_ima_measure_* function is called. It waits
until measure_idx matches the saved value of update_idx, ensuring that
the updates and measurements happen in the same order if there are
multiple processes changing the device at the same time. Then it
measures the device, updates measure_idx, and wakes up any other
process waiting to do a measurement. This makes sure that the
measurements are serialized and done in the order that the _hash_lock
was acquired in. But they only block other measurements for the same
device, which are unlikely to happen at the same time.
do_resume() is trickier, because it removes the inactive table while
holding the _hash_lock, but doesn't hold it while updating md->map. To
make sure it is also ordered, the IMA code grabs the _hash_lock after
md->map is updated. Then it makes sure that the device isn't being
removed and that another do_resume() hasn't already changed the active
table again, and serializes like the other functions do.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
There is no status flag that is is used for STATUSTYPE_IMA type
status() calls, and STATUSTYPE_IMA itself is not a valid
status flag.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Tony Asleson (using Claude) found a buffer overflow in dm-ioctl in the
function retrieve_status:
1. The code in retrieve_status checks that the output string fits into
the output buffer and writes the output string there
2. Then, the code aligns the "outptr" variable to the next 8-byte
boundary:
outptr = align_ptr(outptr);
3. The alignment doesn't check overflow, so outptr could point past the
buffer end
4. The "for" loop is iterated again, it executes:
remaining = len - (outptr - outbuf);
5. If "outptr" points past "outbuf + len", the arithmetics wraps around
and the variable "remaining" contains unusually high number
6. With "remaining" being high, the code writes more data past the end of
the buffer
Luckily, this bug has no security implications because:
1. Only root can issue device mapper ioctls
2. The commonly used libraries that communicate with device mapper
(libdevmapper and devicemapper-rs) use buffer size that is aligned to
8 bytes - thus, "outptr = align_ptr(outptr)" can't overshoot the input
buffer and the bug can't happen accidentally
Reported-by: Tony Asleson <tasleson@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Bryn M. Reeves <bmr@redhat.com>
Cc: stable@vger.kernel.org
The command "dmsetup remove_all" may take a long time (a minute for
removing 1000 devices), so make it interruptible with fatal signals.
For better readability, the bool arguments were changed to flags.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
If dm_hash_remove_all was called from dm_deferred_remove, it would write
a warning "remove_all left %d open device(s)" if there are some other
devices active.
The warning is bogus, so let's disable it in this case.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 2c140a246d ("dm: allow remove to be deferred")
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
This reverts commit f6007dce0c.
Commit f6007dce0c ("dm: fix a race condition in retrieve_deps") was
added to fix a race between retrieving the list of dm table devices and
multipath_message() modifying the list of table devices. But Commit
a48f6b82c5 ("dm mpath: don't call dm_get_device in multipath_message")
removed the call to dm_get_device() from multipath_message(). After that
commit, the only calls to dm_get_device() and dm_put_device() are in
target constructors and destructors, so the race with retrieve_deps() is
no longer possible.
Suggested-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Multipath cannot directly provide failover for ioctls in the kernel
because it doesn't know what each ioctl means and which result could
indicate a path error. Userspace generally knows what the ioctl it
issued means and if it might be a path error, but neither does it know
which path the ioctl took nor does it necessarily have the privileges to
fail a path using the control device.
In order to allow userspace to address this situation, implement a
DM_MPATH_PROBE_PATHS ioctl that prompts the dm-mpath driver to probe all
active paths in the current path group to see whether they still work,
and fail them if not. If this returns success, userspace can retry the
ioctl and expect that the previously hit bad path is now failed (or
working again).
The immediate motivation for this is the use of SG_IO in QEMU for SCSI
passthrough. Following a failed SG_IO ioctl, QEMU will trigger probing
to ensure that all active paths are actually alive, so that retrying
SG_IO at least has a lower chance of failing due to a path error.
However, the problem is broader than just SG_IO (it affects any ioctl),
and if applications need failover support for other ioctls, the same
probing can be used.
This is not implemented on the DM control device, but on the DM mpath
block devices, to allow all users who have access to such a block device
to make use of this interface, specifically to implement failover for
ioctls. For the same reason, it is also unprivileged. Its implementation
is effectively just a bunch of reads, which could already be issued by
userspace, just without any guarantee that all the rights paths are
selected.
The probing implemented here is done fully synchronously path by path;
probing all paths concurrently is left as an improvement for the future.
Co-developed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
It is possible to spam the kernel log with a misbehaving user process that
is passing incorrect dm ioctls to /dev/mapper/control. Use a rate limit
on these error messages to reduce the noise.
These errors were hit when running the stress-ng's device test.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Acked-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
If the dm_resume method is called on a device that is not suspended, the
method will suspend the device briefly, before resuming it (so that the
table will be swapped).
However, there was a bug that the return value of dm_suspended_md was not
checked. dm_suspended_md may return an error when it is interrupted by a
signal. In this case, do_resume would call dm_swap_table, which would
return -EINVAL.
This commit fixes the logic, so that error returned by dm_suspend is
checked and the resume operation is undone.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Cc: stable@vger.kernel.org
The kvmalloc function fails with a warning if the size is larger than
INT_MAX. The warning was triggered by a syscall testing robot.
In order to avoid the warning, this commit limits the number of targets to
1048576 and the size of the parameter area to 1073741824.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
We expect `spec->target_type` to be NUL-terminated based on its use with
a format string after `dm_table_add_target()` is called
| r = dm_table_add_target(table, spec->target_type,
| (sector_t) spec->sector_start,
| (sector_t) spec->length,
| target_params);
... wherein `spec->target_type` is passed as parameter `type` and later
printed with DMERR:
| DMERR("%s: %s: unknown target type", dm_device_name(t->md), type);
It appears that `spec` is not zero-allocated and thus NUL-padding may be
required in this ioctl context.
Considering the above, a suitable replacement is `strscpy_pad` due to
the fact that it guarantees NUL-termination whilst maintaining the
NUL-padding behavior that strncpy provides.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
There's a race condition in the multipath target when retrieve_deps
races with multipath_message calling dm_get_device and dm_put_device.
retrieve_deps walks the list of open devices without holding any lock
but multipath may add or remove devices to the list while it is
running. The end result may be memory corruption or use-after-free
memory access.
See this description of a UAF with multipath_message():
https://listman.redhat.com/archives/dm-devel/2022-October/052373.html
Fix this bug by introducing a new rw semaphore "devices_lock". We grab
devices_lock for read in retrieve_deps and we grab it for write in
dm_get_device and dm_put_device.
Reported-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Tested-by: Li Lingfeng <lilingfeng3@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
- Fix DM crypt target's crypt_ctr_cipher_new return value on invalid
AEAD cipher.
- Fix DM flakey testing target's write bio corruption feature to
corrupt the data of a cloned bio instead of the original.
- Add random_read_corrupt and random_write_corrupt features to DM
flakey target.
- Fix ABBA deadlock in DM thin metadata by resetting associated bufio
client rather than destroying and recreating it.
- A couple other small DM thinp cleanups.
- Update DM core to support disabling block core IO stats accounting
and optimize away code that isn't needed if stats are disabled.
- Other small DM core cleanups.
- Improve DM integrity target to not require so much memory on 32 bit
systems. Also only allocate the recalculate buffer as needed (and
increasingly reduce its size on allocation failure).
- Update DM integrity to use %*ph for printing hexdump of a small
buffer. Also update DM integrity documentation.
- Various DM core ioctl interface hardening. Now more careful about
alignment of structures and processing of input passed to the kernel
from userspace. Also disallow the creation of DM devices named
"control", "." or ".."
- Eliminate GFP_NOIO workarounds for __vmalloc and kvmalloc in DM
core's ioctl and bufio code.
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Merge tag 'for-6.5/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper updates from Mike Snitzer:
- Update DM crypt to allocate compound pages if possible
- Fix DM crypt target's crypt_ctr_cipher_new return value on invalid
AEAD cipher
- Fix DM flakey testing target's write bio corruption feature to
corrupt the data of a cloned bio instead of the original
- Add random_read_corrupt and random_write_corrupt features to DM
flakey target
- Fix ABBA deadlock in DM thin metadata by resetting associated bufio
client rather than destroying and recreating it
- A couple other small DM thinp cleanups
- Update DM core to support disabling block core IO stats accounting
and optimize away code that isn't needed if stats are disabled
- Other small DM core cleanups
- Improve DM integrity target to not require so much memory on 32 bit
systems. Also only allocate the recalculate buffer as needed (and
increasingly reduce its size on allocation failure)
- Update DM integrity to use %*ph for printing hexdump of a small
buffer. Also update DM integrity documentation
- Various DM core ioctl interface hardening. Now more careful about
alignment of structures and processing of input passed to the kernel
from userspace.
Also disallow the creation of DM devices named "control", "." or ".."
- Eliminate GFP_NOIO workarounds for __vmalloc and kvmalloc in DM
core's ioctl and bufio code
* tag 'for-6.5/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (28 commits)
dm: get rid of GFP_NOIO workarounds for __vmalloc and kvmalloc
dm integrity: scale down the recalculate buffer if memory allocation fails
dm integrity: only allocate recalculate buffer when needed
dm integrity: reduce vmalloc space footprint on 32-bit architectures
dm ioctl: Refuse to create device named "." or ".."
dm ioctl: Refuse to create device named "control"
dm ioctl: Avoid double-fetch of version
dm ioctl: structs and parameter strings must not overlap
dm ioctl: Avoid pointer arithmetic overflow
dm ioctl: Check dm_target_spec is sufficiently aligned
Documentation: dm-integrity: Document an example of how the tunables relate.
Documentation: dm-integrity: Document default values.
Documentation: dm-integrity: Document the meaning of "buffer".
Documentation: dm-integrity: Fix minor grammatical error.
dm integrity: Use %*ph for printing hexdump of a small buffer
dm thin: disable discards for thin-pool if no_discard_passdown
dm: remove stale/redundant dm_internal_{suspend,resume} prototypes in dm.h
dm: skip dm-stats work in alloc_io() unless needed
dm: avoid needless dm_io access if all IO accounting is disabled
dm: support turning off block-core's io stats accounting
...
In the past, the function __vmalloc didn't respect the GFP flags - it
allocated memory with the provided gfp flags, but it allocated page tables
with GFP_KERNEL. This was fixed in commit 451769ebb7 ("mm/vmalloc:
alloc GFP_NO{FS,IO} for vmalloc") so the memalloc_noio_{save,restore}
workaround is no longer needed.
The function kvmalloc didn't like flags different from GFP_KERNEL. This
was fixed in commit a421ef3030 ("mm: allow !GFP_KERNEL allocations
for kvmalloc"), so kvmalloc can now be called with GFP_NOIO.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Merge tag 'for-6.5/block-2023-06-23' of git://git.kernel.dk/linux
Pull block updates from Jens Axboe:
- NVMe pull request via Keith:
- Various cleanups all around (Irvin, Chaitanya, Christophe)
- Better struct packing (Christophe JAILLET)
- Reduce controller error logs for optional commands (Keith)
- Support for >=64KiB block sizes (Daniel Gomez)
- Fabrics fixes and code organization (Max, Chaitanya, Daniel
Wagner)
- bcache updates via Coly:
- Fix a race at init time (Mingzhe Zou)
- Misc fixes and cleanups (Andrea, Thomas, Zheng, Ye)
- use page pinning in the block layer for dio (David)
- convert old block dio code to page pinning (David, Christoph)
- cleanups for pktcdvd (Andy)
- cleanups for rnbd (Guoqing)
- use the unchecked __bio_add_page() for the initial single page
additions (Johannes)
- fix overflows in the Amiga partition handling code (Michael)
- improve mq-deadline zoned device support (Bart)
- keep passthrough requests out of the IO schedulers (Christoph, Ming)
- improve support for flush requests, making them less special to deal
with (Christoph)
- add bdev holder ops and shutdown methods (Christoph)
- fix the name_to_dev_t() situation and use cases (Christoph)
- decouple the block open flags from fmode_t (Christoph)
- ublk updates and cleanups, including adding user copy support (Ming)
- BFQ sanity checking (Bart)
- convert brd from radix to xarray (Pankaj)
- constify various structures (Thomas, Ivan)
- more fine grained persistent reservation ioctl capability checks
(Jingbo)
- misc fixes and cleanups (Arnd, Azeem, Demi, Ed, Hengqi, Hou, Jan,
Jordy, Li, Min, Yu, Zhong, Waiman)
* tag 'for-6.5/block-2023-06-23' of git://git.kernel.dk/linux: (266 commits)
scsi/sg: don't grab scsi host module reference
ext4: Fix warning in blkdev_put()
block: don't return -EINVAL for not found names in devt_from_devname
cdrom: Fix spectre-v1 gadget
block: Improve kernel-doc headers
blk-mq: don't insert passthrough request into sw queue
bsg: make bsg_class a static const structure
ublk: make ublk_chr_class a static const structure
aoe: make aoe_class a static const structure
block/rnbd: make all 'class' structures const
block: fix the exclusive open mask in disk_scan_partitions
block: add overflow checks for Amiga partition support
block: change all __u32 annotations to __be32 in affs_hardblocks.h
block: fix signed int overflow in Amiga partition support
block: add capacity validation in bdev_add_partition()
block: fine-granular CAP_SYS_ADMIN for Persistent Reservation
block: disallow Persistent Reservation on partitions
reiserfs: fix blkdev_put() warning from release_journal_dev()
block: fix wrong mode for blkdev_get_by_dev() from disk_scan_partitions()
block: document the holder argument to blkdev_get_by_path
...
Using either of these is going to greatly confuse userspace, as they are
not valid symlink names and so creating the usual /dev/mapper/NAME
symlink will not be possible. As creating a device with either of these
names is almost certainly a userspace bug, just error out.
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Typical userspace setups create a symlink under /dev/mapper with the
name of the device, but /dev/mapper/control is reserved for DM's control
device. Therefore, trying to create such a device is almost certain to
be a userspace bug.
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
The version is fetched once in check_version(), which then does some
validation and then overwrites the version in userspace with the API
version supported by the kernel. copy_params() then fetches the version
from userspace *again*, and this time no validation is done. The result
is that the kernel's version number is completely controllable by
userspace, provided that userspace can win a race condition.
Fix this flaw by not copying the version back to the kernel the second
time. This is not exploitable as the version is not further used in the
kernel. However, it could become a problem if future patches start
relying on the version field.
Cc: stable@vger.kernel.org
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
The NUL terminator for each target parameter string must precede the
following 'struct dm_target_spec'. Otherwise, dm_split_args() might
corrupt this struct. Furthermore, the first 'struct dm_target_spec'
must come after the 'struct dm_ioctl', as if it overlaps too much
dm_split_args() could corrupt the 'struct dm_ioctl'.
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Especially on 32-bit systems, it is possible for the pointer
arithmetic to overflow and cause a userspace pointer to be
dereferenced in the kernel.
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Otherwise subsequent code, if given malformed input, could dereference
a misaligned 'struct dm_target_spec *'.
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> # use %zu
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
As described in commit 38d11da522 ("dm: don't lock fs when the map is
NULL in process of resume"), a deadlock may be triggered between
do_resume() and do_mount().
This commit preserves the fix from commit 38d11da522 but moves it to
where it also serves to fix a similar deadlock between do_suspend()
and do_mount(). It does so, if the active map is NULL, by clearing
DM_SUSPEND_LOCKFS_FLAG in dm_suspend() which is called by both
do_suspend() and do_resume().
Fixes: 38d11da522 ("dm: don't lock fs when the map is NULL in process of resume")
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
The only overlap between the block open flags mapped into the fmode_t and
other uses of fmode_t are FMODE_READ and FMODE_WRITE. Define a new
blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and
->ioctl and stop abusing fmode_t.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com> [rnbd]
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit fa247089de ("dm: requeue IO if mapping table not yet available")
added a detection of whether the mapping table is available in the IO
submission process. If the mapping table is unavailable, it returns
BLK_STS_RESOURCE and requeues the IO.
This can lead to the following deadlock problem:
dm create mount
ioctl(DM_DEV_CREATE_CMD)
ioctl(DM_TABLE_LOAD_CMD)
do_mount
vfs_get_tree
ext4_get_tree
get_tree_bdev
sget_fc
alloc_super
// got &s->s_umount
down_write_nested(&s->s_umount, ...);
ext4_fill_super
ext4_load_super
ext4_read_bh
submit_bio
// submit and wait io end
ioctl(DM_DEV_SUSPEND_CMD)
dev_suspend
do_resume
dm_suspend
__dm_suspend
lock_fs
freeze_bdev
get_active_super
grab_super
// wait for &s->s_umount
down_write(&s->s_umount);
dm_swap_table
__bind
// set md->map(can't get here)
IO will be continuously requeued while holding the lock since mapping
table is NULL. At the same time, mapping table won't be set since the
lock is not available.
Like request-based DM, bio-based DM also has the same problem.
It's not proper to just abort IO if the mapping table not available.
So clear DM_SKIP_LOCKFS_FLAG when the mapping table is NULL, this
allows the DM table to be loaded and the IO submitted upon resume.
Fixes: fa247089de ("dm: requeue IO if mapping table not yet available")
Cc: stable@vger.kernel.org
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
syzkaller found the following problematic rwsem locking (with write
lock already held):
down_read+0x9d/0x450 kernel/locking/rwsem.c:1509
dm_get_inactive_table+0x2b/0xc0 drivers/md/dm-ioctl.c:773
__dev_status+0x4fd/0x7c0 drivers/md/dm-ioctl.c:844
table_clear+0x197/0x280 drivers/md/dm-ioctl.c:1537
In table_clear, it first acquires a write lock
https://elixir.bootlin.com/linux/v6.2/source/drivers/md/dm-ioctl.c#L1520
down_write(&_hash_lock);
Then before the lock is released at L1539, there is a path shown above:
table_clear -> __dev_status -> dm_get_inactive_table -> down_read
https://elixir.bootlin.com/linux/v6.2/source/drivers/md/dm-ioctl.c#L773
down_read(&_hash_lock);
It tries to acquire the same read lock again, resulting in the deadlock
problem.
Fix this by moving table_clear()'s __dev_status() call to after its
up_write(&_hash_lock);
Cc: stable@vger.kernel.org
Reported-by: Zheng Zhang <zheng.zhang@email.ucr.edu>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
__hash_remove() removes hash_cell with _hash_lock locked, so acquiring
_hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
have not been removed and hc->md must still be md.
__hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
as NULL. So in dm_copy_name_and_uuid(), after acquiring
dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
hc must still be alive and hc->md must still be md.
Remove the unnecessary hc->md != md checks when using dm_get_mdptr()
with _hash_lock or dm_hash_cells_mutex acquired.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Also update dm_early_create() to take _hash_lock when calling both
__get_name_cell and __hash_remove -- given dm_early_create()'s early
boot usecase this locking isn't about correctness but it allows
lockdep_assert_held() to be added to __hash_remove.
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
