kernel/linux.git/fs, branch v6.6.143

smb: client: require net admin for CIFS SWN netlink

2026-06-19T11:39:38+00:00

[ Upstream commit d1ebfce2c1d161186a82e77590bf7da2ea1bce91 ] CIFS_GENL_CMD_SWN_NOTIFY is the userspace witness-notify command. The intended sender is the cifs.witness helper, but the generic-netlink operation currently has no capability flag, so any local process can send RESOURCE_CHANGE or CLIENT_MOVE notifications to the in-kernel witness handler. The same family exposes CIFS_GENL_MCGRP_SWN without multicast-group capability flags. Register messages sent to that group include the witness registration id and, for NTLM-authenticated mounts, the username, domain, and password attributes copied from the CIFS session. An unprivileged local process should not be able to join that group and receive those messages. Require CAP_NET_ADMIN for incoming SWN_NOTIFY commands with GENL_ADMIN_PERM, and require CAP_NET_ADMIN over the network namespace for joining the SWN multicast group with GENL_MCAST_CAP_NET_ADMIN. The cifs.witness service runs with the privileges needed for both operations. Fixes: fed979a7e082 ("cifs: Set witness notification handler for messages from userspace daemon") Cc: stable@vger.kernel.org Signed-off-by: Michael Bommarito Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ksmbd: fix OOB write in QUERY_INFO for compound requests

2026-06-19T11:39:38+00:00

commit fda9522ed6afaec45cabc198d8492270c394c7bc upstream. When a compound request such as READ + QUERY_INFO(Security) is received, and the first command (READ) consumes most of the response buffer, ksmbd could write beyond the allocated buffer while building a security descriptor. The root cause was that smb2_get_info_sec() checked buffer space using ppntsd_size from xattr, while build_sec_desc() often synthesized a significantly larger descriptor from POSIX ACLs. This patch introduces smb_acl_sec_desc_scratch_len() to accurately compute the final descriptor size beforehand, performs proper buffer checking with smb2_calc_max_out_buf_len(), and uses exact-sized allocation + iov pinning. Cc: stable@vger.kernel.org Fixes: e2b76ab8b5c9 ("ksmbd: add support for read compound") Signed-off-by: Asim Viladi Oglu Manizada Signed-off-by: Namjae Jeon Signed-off-by: Steve French [ In v6.6, replace KSMBD_DEFAULT_GFP with GFP_KERNEL per commit 0066f623bce8 ("ksmbd: use __GFP_RETRY_MAYFAIL"). ] Signed-off-by: Alva Lan Signed-off-by: Greg Kroah-Hartman

fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling

2026-06-19T11:39:37+00:00

commit 00633c4683828acd5256fa8d5163f440d74bbe71 upstream. A SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock can occur in send_sigio() and send_sigurg() when a process group receives a signal. When FASYNC is configured for a process group (PIDTYPE_PGID), both functions use read_lock(&tasklist_lock) to traverse the task list. However, they are frequently called from softirq context: - send_sigio() via input_inject_event -> kill_fasync - send_sigurg() via tcp_check_urg -> sk_send_sigurg (NET_RX_SOFTIRQ) The deadlock is caused by the rwlock writer fairness mechanism: 1. CPU 0 (process context) holds read_lock(&tasklist_lock) in do_wait(). 2. CPU 1 (process context) attempts write_lock(&tasklist_lock) in fork() or exit() and spins, which blocks all new readers. 3. CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception). 4. The softirq calls send_sigurg() and attempts to acquire read_lock(&tasklist_lock), deadlocking because CPU 1 is waiting. Since PID hashing and do_each_pid_task() traversals are already RCU-protected, the read_lock on tasklist_lock is no longer strictly required for safe traversal. Fix this by replacing tasklist_lock with rcu_read_lock(), aligning the process group signaling path with the single-PID path. This also mitigates a potential remote denial of service vector via TCP URG packets. Lockdep splat: ===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected [...] Chain exists of: &dev->event_lock --> &f_owner->lock --> tasklist_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tasklist_lock); local_irq_disable(); lock(&dev->event_lock); lock(&f_owner->lock); lock(&dev->event_lock); *** DEADLOCK *** Reviewed-by: Jeff Layton Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn> Link: https://patch.msgid.link/20260523135210.590928-1-w15303746062@163.com Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Greg Kroah-Hartman

fuse: reject fuse_notify() pagecache ops on directories

2026-06-19T11:39:34+00:00

commit 9c954499d43aefac01c5dfb57a82b13d2dcf4b94 upstream. The operations FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE allow the FUSE daemon to actively write/read pagecache contents. For directories with FOPEN_CACHE_DIR, the pagecache is used as kernel-internal cache storage, and userspace is not supposed to have direct access to this cache - in particular, fuse_parse_cache() will hit WARN_ON() if the cache contains bogus data. Reject FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE on anything other than regular files with -EINVAL. Fixes: 5d7bc7e8680c ("fuse: allow using readdir cache") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn Link: https://patch.msgid.link/20260519-fuse-dir-pagecache-v2-1-5428fa48e175@google.com Acked-by: Miklos Szeredi Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Greg Kroah-Hartman

ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL

2026-06-19T11:39:32+00:00

commit f580d27e8928828693df44ba2db0fffdbe11dfea upstream. A deferred byte-range lock (an SMB2_LOCK that blocks) registers an async work on conn->async_requests via setup_async_work(), with cancel_fn = smb2_remove_blocked_lock and cancel_argv[0] pointing at the struct file_lock. When the request is cancelled, the worker frees the file_lock with locks_free_lock() and takes the cancelled early-exit, which "goto out"s and never reaches release_async_work() -- the only site that unlinks the work from conn->async_requests and clears cancel_fn/cancel_argv. The work therefore stays matchable on async_requests with a live cancel_fn pointing at the freed file_lock, until connection teardown finally runs release_async_work(). smb2_cancel() fires cancel_fn unconditionally with no state guard, so a second SMB2_CANCEL for the same AsyncId, arriving in that window, re-runs smb2_remove_blocked_lock() on the freed file_lock -- a slab use-after-free: BUG: KASAN: slab-use-after-free in __locks_delete_block __locks_delete_block locks_delete_block ksmbd_vfs_posix_lock_unblock smb2_remove_blocked_lock smb2_cancel <- 2nd SMB2_CANCEL fires cancel_fn handle_ksmbd_work Allocated by ...: locks_alloc_lock <- smb2_lock Freed by ...: locks_free_lock <- smb2_lock (cancelled branch) ... cache file_lock_cache of size 192 Reproduced on mainline with KASAN by an authenticated SMB client. Skip a work whose state is already KSMBD_WORK_CANCELLED so its cancel callback cannot be fired a second time. Cc: stable@vger.kernel.org Signed-off-by: Gil Portnoy Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

iomap: don't revert iov_iter on partially completed buffered writes

2026-06-19T11:39:29+00:00

Gregg reports that the iomap retry behavior for nonblocking (nowait) append writes is broken. The problem occurs when an append write is first submitted in non-blocking mode (i.e. via io_uring), partially completes before hitting -EAGAIN, and then is resubmitted from blocking context. The specific problem is that at least one iteration of the loop in iomap_write_iter() completes in non-blocking context and thus has bumped i_size. The next iteration hits -EAGAIN, reverts the iov_iter and returns. io_uring retries the entire append write from blocking context, but since i_size has already been increased, the data that was partially written on the first attempt is rewritten at the new i_size. This is essentially an intra-write data corruption since the data written to the file does not reflect the write from userspace. This problem is already fixed on master as of commit 1a1a3b574b97 ("iomap: advance the iter directly on buffered writes"). That commit was primarily intended to clean up iomap iter state tracking, but it also happened to remove the iov_iter revert and thus accidentally fix this problem as well. Without the revert, iomap will commit partial progress internally and loop once more before it more than likely hits -EAGAIN and returns partial progress consistent with the inode updates. This means the blocking retry from io_uring will pick up where the first attempt left off at the current i_size and perform the remainder of the write correctly. Cc: Fixes: 18e419f6e80a ("iomap: Return -EAGAIN from iomap_write_iter()") Reported-by: Gregg Leventhal Reported-by: Eric Hagberg Signed-off-by: Brian Foster Signed-off-by: Sasha Levin

ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers

2026-06-19T11:39:25+00:00

[ Upstream commit b003086d76968298f22e7cf62239833b5a3a06b1 ] smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 -- a remotely triggerable oops. Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown. Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Assisted-by: Henry (Claude):claude-opus-4 Signed-off-by: Gil Portnoy Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin

ksmbd: OOB read regression in smb_check_perm_dacl() ACE-walk loops

2026-06-19T11:39:20+00:00

commit 0e60dafe97eca61721f3db456f97d97a80c6c8ae upstream. Commit d07b26f39246 ("ksmbd: require minimum ACE size in smb_check_perm_dacl()") introduced a transposed bounds check: if (offsetof(struct smb_ace, sid) + aces_size < CIFS_SID_BASE_SIZE) Since offsetof(..sid) is 8 and CIFS_SID_BASE_SIZE is 8, this evaluates to `aces_size < 0`. Because `aces_size` is always non-negative, this check becomes dead code and never breaks the loop. Worse, that commit removed the old 4-byte guard, meaning the loop now reads `ace->size` (offset 2) even when `aces_size` is 0-3 bytes. This re-opens a 2-byte heap out-of-bounds (OOB) read past the pntsd allocation during subsequent SMB2_CREATE operations. Fix this by properly transposing the comparison to require at least 16 bytes (8-byte offset + 8-byte SID base), matching the correct form used in smb_inherit_dacl(). Fixes: d07b26f39246 ("ksmbd: require minimum ACE size in smb_check_perm_dacl()") Cc: stable@vger.kernel.org Signed-off-by: Ali Ganiyev Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

hpfs: fix a crash if hpfs_map_dnode_bitmap fails

2026-06-19T11:39:16+00:00

commit 974820a59efde7c1a7e1260bcfe9bb81f833cc9f upstream. If hpfs_map_dnode_bitmap fails, the code would call hpfs_brelse4 on uninitialized quad buffer head, causing a crash. Signed-off-by: Mikulas Patocka Reported-by: Farhad Alemi Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE

2026-06-19T11:39:11+00:00

[ Upstream commit cc57232cae23c0df91b4a59d0f519141ce9b5b02 ] FSCTL_SET_SPARSE in fsctl_set_sparse() modifies the file's sparse attribute and saves it through xattr without any permission checks. This exposes two issues: 1) A client on a read-only share can change the sparse attribute on files it opened, even though the share is read-only. Other FSCTL write operations already check test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE), but FSCTL_SET_SPARSE does not. 2) Even on writable shares, clients without FILE_WRITE_DATA or FILE_WRITE_ATTRIBUTES access should not modify the sparse attribute. Similar handle-level checks exist in other functions but are missing here. Add both share-level writable check and per-handle access check. Use goto out on error to avoid leaking file references. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: Namjae Jeon Cc: Sergey Senozhatsky Cc: Steve French Signed-off-by: Sean Shen Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin