fuse_iomap_writeback_range() appends one folio pointer and one
fuse_folio_desc for every dirty range that is merged into the current
writeback request. The merge decision checks the byte budget against
fc->max_pages and fc->max_write, but it does not check whether the folio
and descriptor arrays still have another free slot.
This is not sufficient for fuseblk, where the filesystem block size can
be smaller than PAGE_SIZE. With writeback cache enabled and max_pages
negotiated as one, contiguous sub-page dirty ranges can fit within the
byte budget while spanning more than one folio. The next append can then
write past the one-slot folios and descs arrays.
Split the request when the number of already attached folios has reached
fc->max_pages. This keeps the folio/descriptor slot accounting in sync
with the send decision.
Fixes: ef7e7cbb32 ("fuse: use iomap for writeback")
Cc: stable@vger.kernel.org
Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Junxi Qian <qjx1298677004@gmail.com>
Link: https://patch.msgid.link/20260506122415.205340-1-qjx1298677004@gmail.com
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull vfs fixes from Christian Brauner:
- eventpoll: fix ep_remove() UAF and follow-up cleanup
- fs: aio: set VMA_DONTCOPY_BIT in mmap to fix NULL-pointer-dereference
error
- writeback: Fix use after free in inode_switch_wbs_work_fn()
- fuse: reject oversized dirents in page cache
- fs: aio: reject partial mremap to avoid Null-pointer-dereference
error
- nstree: fix func. parameter kernel-doc warnings
- fs: Handle multiply claimed blocks more gracefully with mmb
* tag 'vfs-7.1-rc1.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
eventpoll: drop vestigial epi->dying flag
eventpoll: drop dead bool return from ep_remove_epi()
eventpoll: refresh eventpoll_release() fast-path comment
eventpoll: move f_lock acquisition into ep_remove_file()
eventpoll: fix ep_remove struct eventpoll / struct file UAF
eventpoll: move epi_fget() up
eventpoll: rename ep_remove_safe() back to ep_remove()
eventpoll: drop vestigial __ prefix from ep_remove_{file,epi}()
eventpoll: kill __ep_remove()
eventpoll: split __ep_remove()
eventpoll: use hlist_is_singular_node() in __ep_remove()
fs: Handle multiply claimed blocks more gracefully with mmb
nstree: fix func. parameter kernel-doc warnings
fs: aio: reject partial mremap to avoid Null-pointer-dereference error
fuse: reject oversized dirents in page cache
writeback: Fix use after free in inode_switch_wbs_work_fn()
fs: aio: set VMA_DONTCOPY_BIT in mmap to fix NULL-pointer-dereference error
fuse_add_dirent_to_cache() computes a serialized dirent size from the
server-controlled namelen field and copies the dirent into a single
page-cache page. The existing logic only checks whether the dirent fits
in the remaining space of the current page and advances to a fresh page
if not. It never checks whether the dirent itself exceeds PAGE_SIZE.
As a result, a malicious FUSE server can return a dirent with
namelen=4095, producing a serialized record size of 4120 bytes. On 4 KiB
page systems this causes memcpy() to overflow the cache page by 24 bytes
into the following kernel page.
Reject dirents that cannot fit in a single page before copying them into
the readdir cache.
Fixes: 69e3455115 ("fuse: allow caching readdir")
Cc: stable@vger.kernel.org # v6.16+
Assisted-by: Bynario AI
Signed-off-by: Samuel Page <sam@bynar.io>
Reported-by: Qi Tang <tpluszz77@gmail.com>
Reported-by: Zijun Hu <nightu@northwestern.edu>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://patch.msgid.link/20260420090139.662772-1-mszeredi@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull fuse update from Miklos Szeredi:
- Fix possible hang in virtiofs when cleaning up a DAX inode (Sergio
Lopez)
- Fix a warning when using large folio as the source of SPLICE_F_MOVE
on the fuse device (Bernd)
- Fix uninitialized value found by KMSAN (Luis Henriques)
- Fix synchronous INIT hang (Miklos)
- Fix race between inode initialization and FUSE_NOTIFY_INVAL_INODE
(Horst)
- Allow fd to be closed after passing fuse device fd to
fsconfig(..., "fd", ...) (Miklos)
- Support FSCONFIG_SET_FD for "fd" option (Miklos)
- Misc fixes and cleanups
* tag 'fuse-update-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (21 commits)
fuse: support FSCONFIG_SET_FD for "fd" option
fuse: clean up device cloning
fuse: don't require /dev/fuse fd to be kept open during mount
fuse: add refcount to fuse_dev
fuse: create fuse_dev on /dev/fuse open instead of mount
fuse: check connection state on notification
fuse: fuse_dev_ioctl_clone() should wait for device file to be initialized
fuse: fix inode initialization race
fuse: abort on fatal signal during sync init
fuse: fix uninit-value in fuse_dentry_revalidate()
fuse: use offset_in_page() for page offset calculations
fuse: use DIV_ROUND_UP() for page count calculations
fuse: simplify logic in fuse_notify_store() and fuse_retrieve()
fuse: validate outarg offset and size in notify store/retrieve
fuse: Check for large folio with SPLICE_F_MOVE
fuse: quiet down complaints in fuse_conn_limit_write
fuse: drop unnecessary argument from fuse_lookup_init()
fuse: fix premature writetrhough request for large folio
fuse: refactor duplicate queue teardown operation
virtiofs: add FUSE protocol validation
...
Pull LSM updates from Paul Moore:
"We only have five patches in the LSM tree, but three of the five are
for an important bugfix relating to overlayfs and the mmap() and
mprotect() access controls for LSMs. Highlights below:
- Fix problems with the mmap() and mprotect() LSM hooks on overlayfs
As we are dealing with problems both in mmap() and mprotect() there
are essentially two components to this fix, spread across three
patches with all marked for stable.
The simplest portion of the fix is the creation of a new LSM hook,
security_mmap_backing_file(), that is used to enforce LSM mmap()
access controls on backing files in the stacked/overlayfs case. The
existing security_mmap_file() does not have visibility past the
user file. You can see from the associated SELinux hook callback
the code is fairly straightforward.
The mprotect() fix is a bit more complicated as there is no way in
the mprotect() code path to inspect both the user and backing
files, and bolting on a second file reference to vm_area_struct
wasn't really an option.
The solution taken here adds a LSM security blob and associated
hooks to the backing_file struct that LSMs can use to capture and
store relevant information from the user file. While the necessary
SELinux information is relatively small, a single u32, I expect
other LSMs to require more than that, and a dedicated backing_file
LSM blob provides a storage mechanism without negatively impacting
other filesystems.
I want to note that other LSMs beyond SELinux have been involved in
the discussion of the fixes presented here and they are working on
their own related changes using these new hooks, but due to other
issues those patches will be coming at a later date.
- Use kstrdup_const()/kfree_const() for securityfs symlink targets
- Resolve a handful of kernel-doc warnings in cred.h"
* tag 'lsm-pr-20260410' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
selinux: fix overlayfs mmap() and mprotect() access checks
lsm: add backing_file LSM hooks
fs: prepare for adding LSM blob to backing_file
securityfs: use kstrdup_const() to manage symlink targets
cred: fix kernel-doc warnings in cred.h
Pull vfs integrity updates from Christian Brauner:
"This adds support to generate and verify integrity information (aka
T10 PI) in the file system, instead of the automatic below the covers
support that is currently used.
The implementation is based on refactoring the existing block layer PI
code to be reusable for this use case, and then adding relatively
small wrappers for the file system use case. These are then used in
iomap to implement the semantics, and wired up in XFS with a small
amount of glue code.
Compared to the baseline this does not change performance for writes,
but increases read performance up to 15% for 4k I/O, with the benefit
decreasing with larger I/O sizes as even the baseline maxes out the
device quickly on my older enterprise SSD"
* tag 'vfs-7.1-rc1.integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
xfs: support T10 protection information
iomap: support T10 protection information
iomap: support ioends for buffered reads
iomap: add a bioset pointer to iomap_read_folio_ops
ntfs3: remove copy and pasted iomap code
iomap: allow file systems to hook into buffered read bio submission
iomap: only call into ->submit_read when there is a read_ctx
iomap: pass the iomap_iter to ->submit_read
iomap: refactor iomap_bio_read_folio_range
block: pass a maxlen argument to bio_iov_iter_bounce
block: add fs_bio_integrity helpers
block: make max_integrity_io_size public
block: prepare generation / verification helpers for fs usage
block: add a bdev_has_integrity_csum helper
block: factor out a bio_integrity_setup_default helper
block: factor out a bio_integrity_action helper
Stacked filesystems such as overlayfs do not currently provide the
necessary mechanisms for LSMs to properly enforce access controls on the
mmap() and mprotect() operations. In order to resolve this gap, a LSM
security blob is being added to the backing_file struct and the following
new LSM hooks are being created:
security_backing_file_alloc()
security_backing_file_free()
security_mmap_backing_file()
The first two hooks are to manage the lifecycle of the LSM security blob
in the backing_file struct, while the third provides a new mmap() access
control point for the underlying backing file. It is also expected that
LSMs will likely want to update their security_file_mprotect() callback
to address issues with their mprotect() controls, but that does not
require a change to the security_file_mprotect() LSM hook.
There are a three other small changes to support these new LSM hooks:
* Pass the user file associated with a backing file down to
alloc_empty_backing_file() so it can be included in the
security_backing_file_alloc() hook.
* Add getter and setter functions for the backing_file struct LSM blob
as the backing_file struct remains private to fs/file_table.c.
* Constify the file struct field in the LSM common_audit_data struct to
better support LSMs that need to pass a const file struct pointer into
the common LSM audit code.
Thanks to Arnd Bergmann for identifying the missing EXPORT_SYMBOL_GPL()
and supplying a fixup.
Cc: stable@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-unionfs@vger.kernel.org
Cc: linux-erofs@lists.ozlabs.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This is not only cleaner to use in userspace (no need to sprintf the fd to
a string) but also allows userspace to detect that the devfd can be closed
after the fsconfig call.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
- fuse_mutex is not needed for device cloning, because fuse_dev_install()
uses cmpxcg() to set fud->fc, which prevents races between clone/mount
or clone/clone. This makes the logic simpler
- Drop fc->dev_count. This is only used to check in release if the device
is the last clone, but checking list_empty(&fc->devices) is equivalent
after removing the released device from the list. Removing the fuse_dev
before calling fuse_abort_conn() is okay, since the processing and io
lists are now empty for this device.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
With the new mount API the sequence of syscalls would be:
fs_fd = fsopen("fuse", 0);
snprintf(opt, sizeof(opt), "%i", devfd);
fsconfig(fs_fd, FSCONFIG_SET_STRING, "fd", opt, 0);
/* ... */
fsconfig(fs_fd, FSCONFIG_CMD_CREATE, 0, 0, 0);
Current mount code just stores the value of devfd in the fs_context and
uses it in during FSCONFIG_CMD_CREATE, which is inelegant.
Instead grab a reference to the underlying fuse_dev, and use that during
the filesystem creation.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This will make it possible to grab the fuse_dev and subsequently release
the file that it came from.
In the above case, fud->fc will be set to FUSE_DEV_FC_DISCONNECTED to
indicate that this is no longer a functional device.
When trying to assign an fc to such a disconnected fuse_dev, the fc is set
to the disconnected state.
Use atomic operations xchg() and cmpxchg() to prevent races.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Allocate struct fuse_dev when opening the device. This means that unlike
before, ->private_data is always set to a valid pointer.
The use of USE_DEV_SYNC_INIT magic pointer for the private_data is now
replaced with a simple bool sync_init member.
If sync INIT is not set, I/O on the device returns error before mount.
Keep this behavior by checking for the ->fc member. If fud->fc is set, the
mount has succeeded. Testing this used READ_ONCE(file->private_data) and
smp_mb() to try and provide the necessary semantics. Switch this to
smp_store_release() and smp_load_acquire().
Setting fud->fc is protected by fuse_mutex, this is unchanged.
Will need this later so the /dev/fuse open file reference is not held
during FSCONFIG_CMD_CREATE.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Check if the connection is fully initialized and connected before trying to
process a notification form the fuse server.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Use fuse_get_dev() not __fuse_get_dev() on the old fd, since in the case of
synchronous INIT the caller will want to wait for the device file to be
available for cloning, just like I/O wants to wait instead of returning an
error.
Fixes: dfb84c3307 ("fuse: allow synchronous FUSE_INIT")
Cc: stable@vger.kernel.org # v6.18
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fix a race between fuse_iget() and fuse_reverse_inval_inode() where
invalidation can arrive while an inode is being initialized, causing
the invalidation to be lost.
By keeping the inode state I_NEW as long as the attributes are not valid
the invalidation can wait until the inode is fully initialized.
Suggested-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Horst Birthelmer <hbirthelmer@ddn.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When sync init is used and the server exits for some reason (error, crash)
while processing FUSE_INIT, the filesystem creation will hang. The reason
is that while all other threads will exit, the mounting thread (or process)
will keep the device fd open, which will prevent an abort from happening.
This is a regression from the async mount case, where the mount was done
first, and the FUSE_INIT processing afterwards, in which case there's no
such recursive syscall keeping the fd open.
Fixes: dfb84c3307 ("fuse: allow synchronous FUSE_INIT")
Cc: stable@vger.kernel.org # v6.18
Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Bernd Schubert <bernd@bsbernd.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Add a SB_I_NO_DATA_INTEGRITY superblock flag for filesystems that cannot
guarantee data persistence on sync (eg fuse). For superblocks with this
flag set, sync kicks off writeback of dirty inodes but does not wait
for the flusher threads to complete the writeback.
This replaces the per-inode AS_NO_DATA_INTEGRITY mapping flag added in
commit f9a49aa302 ("fs/writeback: skip AS_NO_DATA_INTEGRITY mappings
in wait_sb_inodes()"). The flag belongs at the superblock level because
data integrity is a filesystem-wide property, not a per-inode one.
Having this flag at the superblock level also allows us to skip having
to iterate every dirty inode in wait_sb_inodes() only to skip each inode
individually.
Prior to this commit, mappings with no data integrity guarantees skipped
waiting on writeback completion but still waited on the flusher threads
to finish initiating the writeback. Waiting on the flusher threads is
unnecessary. This commit kicks off writeback but does not wait on the
flusher threads. This change properly addresses a recent report [1] for
a suspend-to-RAM hang seen on fuse-overlayfs that was caused by waiting
on the flusher threads to finish:
Workqueue: pm_fs_sync pm_fs_sync_work_fn
Call Trace:
<TASK>
__schedule+0x457/0x1720
schedule+0x27/0xd0
wb_wait_for_completion+0x97/0xe0
sync_inodes_sb+0xf8/0x2e0
__iterate_supers+0xdc/0x160
ksys_sync+0x43/0xb0
pm_fs_sync_work_fn+0x17/0xa0
process_one_work+0x193/0x350
worker_thread+0x1a1/0x310
kthread+0xfc/0x240
ret_from_fork+0x243/0x280
ret_from_fork_asm+0x1a/0x30
</TASK>
On fuse this is problematic because there are paths that may cause the
flusher thread to block (eg if systemd freezes the user session cgroups
first, which freezes the fuse daemon, before invoking the kernel
suspend. The kernel suspend triggers ->write_node() which on fuse issues
a synchronous setattr request, which cannot be processed since the
daemon is frozen. Or if the daemon is buggy and cannot properly complete
writeback, initiating writeback on a dirty folio already under writeback
leads to writeback_get_folio() -> folio_prepare_writeback() ->
unconditional wait on writeback to finish, which will cause a hang).
This commit restores fuse to its prior behavior before tmp folios were
removed, where sync was essentially a no-op.
[1] https://lore.kernel.org/linux-fsdevel/CAJnrk1a-asuvfrbKXbEwwDSctvemF+6zfhdnuzO65Pt8HsFSRw@mail.gmail.com/T/#m632c4648e9cafc4239299887109ebd880ac6c5c1
Fixes: 0c58a97f91 ("fuse: remove tmp folio for writebacks and internal rb tree")
Reported-by: John <therealgraysky@proton.me>
Cc: stable@vger.kernel.org
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://patch.msgid.link/20260320005145.2483161-2-joannelkoong@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
fuse_dentry_revalidate() may be called with a dentry that didn't had
->d_time initialised. The issue was found with KMSAN, where lookup_open()
calls __d_alloc(), followed by d_revalidate(), as shown below:
=====================================================
BUG: KMSAN: uninit-value in fuse_dentry_revalidate+0x150/0x13d0 fs/fuse/dir.c:394
fuse_dentry_revalidate+0x150/0x13d0 fs/fuse/dir.c:394
d_revalidate fs/namei.c:1030 [inline]
lookup_open fs/namei.c:4405 [inline]
open_last_lookups fs/namei.c:4583 [inline]
path_openat+0x1614/0x64c0 fs/namei.c:4827
do_file_open+0x2aa/0x680 fs/namei.c:4859
[...]
Uninit was created at:
slab_post_alloc_hook mm/slub.c:4466 [inline]
slab_alloc_node mm/slub.c:4788 [inline]
kmem_cache_alloc_lru_noprof+0x382/0x1280 mm/slub.c:4807
__d_alloc+0x55/0xa00 fs/dcache.c:1740
d_alloc_parallel+0x99/0x2740 fs/dcache.c:2604
lookup_open fs/namei.c:4398 [inline]
open_last_lookups fs/namei.c:4583 [inline]
path_openat+0x135f/0x64c0 fs/namei.c:4827
do_file_open+0x2aa/0x680 fs/namei.c:4859
[...]
=====================================================
Reported-by: syzbot+fdebb2dc960aa56c600a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/69917e0d.050a0220.340abe.02e2.GAE@google.com
Fixes: 2396356a94 ("fuse: add more control over cache invalidation behaviour")
Signed-off-by: Luis Henriques <luis@igalia.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Simplify the folio parsing logic in fuse_notify_store() and
fuse_retrieve().
In particular, calculate the index by tracking pos, which allows us to
remove calculating nr_pages, and use "pos" in place of outarg's offset
field.
Suggested-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Add validation checking for outarg offset and outarg size values passed
in by the server. MAX_LFS_FILESIZE is the maximum file size supported.
The fuse_notify_store_out and fuse_notify_retrieve_out structs take in
a uint64_t offset.
Add logic to ensure:
* outarg.offset is less than MAX_LFS_FILESIZE
* outarg.offset + outarg.size cannot exceed MAX_LFS_FILESIZE
* potential uint64_t overflow is fixed when adding outarg.offset and
outarg.size.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
xfstest generic/074 and generic/075 complain result in kernel
warning messages / page dumps.
This is easily reproducible (on 6.19) with
CONFIG_TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ALWAYS=y
CONFIG_TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ALWAYS=y
This just adds a test for large folios fuse_try_move_folio
with the same page copy fallback, but to avoid the warnings
from fuse_check_folio().
Cc: stable@vger.kernel.org
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
Signed-off-by: Horst Birthelmer <hbirthelmer@ddn.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
gcc 15 complains about an uninitialized variable val that is passed by
reference into fuse_conn_limit_write:
control.c: In function ‘fuse_conn_congestion_threshold_write’:
include/asm-generic/rwonce.h:55:37: warning: ‘val’ may be used uninitialized [-Wmaybe-uninitialized]
55 | *(volatile typeof(x) *)&(x) = (val); \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
include/asm-generic/rwonce.h:61:9: note: in expansion of macro ‘__WRITE_ONCE’
61 | __WRITE_ONCE(x, val); \
| ^~~~~~~~~~~~
control.c:178:9: note: in expansion of macro ‘WRITE_ONCE’
178 | WRITE_ONCE(fc->congestion_threshold, val);
| ^~~~~~~~~~
control.c:166:18: note: ‘val’ was declared here
166 | unsigned val;
| ^~~
Unfortunately there's enough macro spew involved in kstrtoul_from_user
that I think gcc gives up on its analysis and sprays the above warning.
AFAICT it's not actually a bug, but we could just zero-initialize the
variable to enable using -Wmaybe-uninitialized to find real problems.
Previously we would use some weird uninitialized_var annotation to quiet
down the warnings, so clearly this code has been like this for quite
some time.
Cc: stable@vger.kernel.org # v5.9
Fixes: 3f649ab728 ("treewide: Remove uninitialized_var() usage")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Junxi Qian
Linus Torvalds
Samuel Page
Paul Moore
Miklos Szeredi
Horst Birthelmer
Joanne Koong
Christoph Hellwig
Luis Henriques
Bernd Schubert
Darrick J. Wong