Pull vfs fixes from Christian Brauner: "The kernfs rbtree is keyed by (hash, ns, name) where the hash is seeded with the raw namespace pointer via init_name_hash(ns). The resulting hash values are exposed to userspace through readdir seek positions, and the pointer-based ordering in kernfs_name_compare() is observable through entry order. Switch from raw pointers to ns_common::ns_id for both hashing and comparison. A preparatory commit first replaces all const void * namespace parameters with const struct ns_common * throughout kernfs, sysfs, and kobject so the code can access ns->ns_id. Also compare the ns_id when hashes match in the rbtree to handle crafted collisions. Also fix eventpoll RCU grace period issue and a cachefiles refcount problem" * tag 'vfs-7.0-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: kernfs: make directory seek namespace-aware kernfs: use namespace id instead of pointer for hashing and comparison kernfs: pass struct ns_common instead of const void * for namespace tags eventpoll: defer struct eventpoll free to RCU grace period cachefiles: fix incorrect dentry refcount in cachefiles_cull()
The rbtree backing kernfs directories is ordered by (hash, ns_id, name) but kernfs_dir_pos() only searches by hash when seeking to a position during readdir. When two nodes from different namespaces share the same hash value, the binary search can land on a node in the wrong namespace. The subsequent skip-forward loop walks rb_next() and may overshoot the correct node, silently dropping an entry from the readdir results. With the recent switch from raw namespace pointers to public namespace ids as hash seeds, computing hash collisions became an offline operation. An unprivileged user could unshare into a new network namespace, create a single interface whose name-hash collides with a target entry in init_net, and cause a victim's seekdir/readdir on /sys/class/net to miss that entry. Fix this by extending the rbtree search in kernfs_dir_pos() to also compare namespace ids when hashes match. Since the rbtree is already ordered by (hash, ns_id, name), this makes the seek land directly in the correct namespace's range, eliminating the wrong-namespace overshoot. Signed-off-by: Christian Brauner <brauner@kernel.org>
kernfs uses the namespace tag as both a hash seed (via init_name_hash()) and a comparison key in the rbtree. The resulting hash values are exposed to userspace through directory seek positions (ctx->pos), and the raw pointer comparisons in kernfs_name_compare() encode kernel pointer ordering into the rbtree layout. This constitutes a KASLR information leak since the hash and ordering derived from kernel pointers can be observed from userspace. Fix this by using the 64-bit namespace id (ns_common::ns_id) instead of the raw pointer value for both hashing and comparison. The namespace id is a stable, non-secret identifier that is already exposed to userspace through other interfaces (e.g., /proc/pid/ns/, ioctl NS_GET_NSID). Introduce kernfs_ns_id() as a helper that extracts the namespace id from a potentially-NULL ns_common pointer, returning 0 for the no-namespace case. All namespace equality checks in the directory iteration and dentry revalidation paths are also switched from pointer comparison to ns_id comparison for consistency. Signed-off-by: Christian Brauner <brauner@kernel.org>
kernfs has historically used const void * to pass around namespace tags used for directory-level namespace filtering. The only current user of this is sysfs network namespace tagging where struct net pointers are cast to void *. Replace all const void * namespace parameters with const struct ns_common * throughout the kernfs, sysfs, and kobject namespace layers. This includes the kobj_ns_type_operations callbacks, kobject_namespace(), and all sysfs/kernfs APIs that accept or return namespace tags. Passing struct ns_common is needed because various codepaths require access to the underlying namespace. A struct ns_common can always be converted back to the concrete namespace type (e.g., struct net) via container_of() or to_ns_common() in the reverse direction. This is a preparatory change for switching to ns_id-based directory iteration to prevent a KASLR pointer leak through the current use of raw namespace pointers as hash seeds and comparison keys. Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull misc fixes from Andrew Morton: "Eight hotfixes. All are cc:stable and seven are for MM. All are singletons - please see the changelogs for details" * tag 'mm-hotfixes-stable-2026-04-06-15-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: ocfs2: fix out-of-bounds write in ocfs2_write_end_inline mm/damon/stat: deallocate damon_call() failure leaking damon_ctx mm/vma: fix memory leak in __mmap_region() mm/memory_hotplug: maintain N_NORMAL_MEMORY during hotplug mm/damon/sysfs: dealloc repeat_call_control if damon_call() fails mm: reinstate unconditional writeback start in balance_dirty_pages() liveupdate: propagate file deserialization failures mm: filemap: fix nr_pages calculation overflow in filemap_map_pages()
KASAN reports a use-after-free write of 4086 bytes in
ocfs2_write_end_inline, called from ocfs2_write_end_nolock during a
copy_file_range splice fallback on a corrupted ocfs2 filesystem mounted on
a loop device. The actual bug is an out-of-bounds write past the inode
block buffer, not a true use-after-free. The write overflows into an
adjacent freed page, which KASAN reports as UAF.
The root cause is that ocfs2_try_to_write_inline_data trusts the on-disk
id_count field to determine whether a write fits in inline data. On a
corrupted filesystem, id_count can exceed the physical maximum inline data
capacity, causing writes to overflow the inode block buffer.
Call trace (crash path):
vfs_copy_file_range (fs/read_write.c:1634)
do_splice_direct
splice_direct_to_actor
iter_file_splice_write
ocfs2_file_write_iter
generic_perform_write
ocfs2_write_end
ocfs2_write_end_nolock (fs/ocfs2/aops.c:1949)
ocfs2_write_end_inline (fs/ocfs2/aops.c:1915)
memcpy_from_folio <-- KASAN: write OOB
So add id_count upper bound check in ocfs2_validate_inode_block() to
alongside the existing i_size check to fix it.
Link: https://lkml.kernel.org/r/20260403063830.3662739-1-joseph.qi@linux.alibaba.com
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reported-by: syzbot+62c1793956716ea8b28a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=62c1793956716ea8b28a
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Heming Zhao <heming.zhao@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pull smb client fix from Steve French: - Fix potential out of bounds read in mount * tag 'v7.0-rc6-smb3-client-fix' of git://git.samba.org/sfrench/cifs-2.6: fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath
In certain situations, ep_free() in eventpoll.c will kfree the epi->ep
eventpoll struct while it still being used by another concurrent thread.
Defer the kfree() to an RCU callback to prevent UAF.
Fixes: f2e467a48287 ("eventpoll: Fix semi-unbounded recursion")
Signed-off-by: Nicholas Carlini <nicholas@carlini.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull smb server fix from Steve French: - Fix out of bound write * tag 'v7.0-rc6-ksmbd-server-fix' of git://git.samba.org/ksmbd: ksmbd: fix OOB write in QUERY_INFO for compound requests
Pull btrfs fix from David Sterba: "One more fix for a potential extent tree corruption due to an unexpected error value. When the search for an extent item failed, it under some circumstances was reported as a success to the caller" * tag 'for-7.0-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref()