From 636abbe7a66d80e179011a31754d55001cd44f63 Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Wed, 2 Sep 2026 13:23:52 +0900 Subject: [PATCH 1/4] ksmbd: fix sparc build with atomic work state Use an unsigned int for the work state so xchg() uses a supported 4-byte operation on sparc. Fixes: d12168084c8c ("ksmbd: safely drain sessions during logoff") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202609021157.8f7Wx34I-lkp@intel.com/ Signed-off-by: Namjae Jeon --- fs/smb/server/ksmbd_work.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/smb/server/ksmbd_work.h b/fs/smb/server/ksmbd_work.h index 5f1d3ebab4fb..0844aa929f55 100644 --- a/fs/smb/server/ksmbd_work.h +++ b/fs/smb/server/ksmbd_work.h @@ -82,7 +82,7 @@ struct ksmbd_work { /* Contiguous SMB2 compression transform owned by this work item. */ void *compress_buf; - unsigned char state; + unsigned int state; /* No response for cancelled request */ bool send_no_response:1; /* Request is encrypted */ From 0e753899627b5e28a9fea8bca98262a6f65a2452 Mon Sep 17 00:00:00 2001 From: Abdifatah Suruur Date: Sat, 29 Aug 2026 18:40:22 +0300 Subject: [PATCH 2/4] ksmbd: fix use-after-free in oplock break notification smb2_oplock_break_noti() reads opinfo->conn without any lock and dereferences it after two allocations which may sleep. When the durable handle owning the oplock is disconnected, session_fd_check() clears opinfo->conn and drops its conn reference under ci->m_lock, and the last ksmbd_conn_put() frees the connection. A break triggered by another connection that races with the teardown can then resurrect the freed connection: ksmbd_conn_get() is a plain atomic_inc, and the queued break work later dereferences the stale conn via ksmbd_conn_write(), a use-after-free reachable by any authenticated client holding a durable batch oplock. Thread the caller's inode into the notification path instead of taking a new reference on it. Every caller of oplock_break() already holds a live ksmbd_file (or an explicit ksmbd_inode_lookup_lock() reference, in the parent lease break paths) on the inode that owns the break target's oplock list, so ci cannot be freed during the call, and its lock can be taken without dereferencing opinfo->o_fp, which a concurrent close may free. Select and pin the connection under ci->m_lock, the same lock session_fd_check() and ksmbd_reopen_durable_fd() use to update opinfo->conn, so a concurrent detach either loses the race to the clear or keeps the connection alive until the notification work releases it. Transfer the reference to the work item and release it on allocation failures. Fixes: b003086d7696 ("ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers") Cc: stable@vger.kernel.org Signed-off-by: Abdifatah Suruur Signed-off-by: Namjae Jeon --- fs/smb/server/oplock.c | 73 +++++++++++++++++++++++++++++++++--------- 1 file changed, 57 insertions(+), 16 deletions(-) diff --git a/fs/smb/server/oplock.c b/fs/smb/server/oplock.c index 58af0fddf39f..1b8c3482d1e4 100644 --- a/fs/smb/server/oplock.c +++ b/fs/smb/server/oplock.c @@ -924,31 +924,69 @@ static void __smb2_oplock_break_noti(struct work_struct *wk) ksmbd_conn_put(conn); } +/* + * Select and pin the connection used for an oplock break before doing any + * allocations which may sleep. The caller of oplock_break() holds a live + * reference on ci (a file being opened, a file being operated on, or an + * explicit ksmbd_inode_lookup_lock() reference in the parent lease break + * paths), so the inode cannot be freed during the call and its lock is + * reachable without dereferencing opinfo->o_fp, which is not pinned by + * the oplock reference and may be freed by a concurrent close. + * + * opinfo->conn is cleared under ci->m_lock by session_fd_check() when the + * durable handle owning the oplock is disconnected, reassigned by + * ksmbd_reopen_durable_fd() under the same lock, and the last + * ksmbd_conn_put() of the old connection frees it. Holding the read lock + * excludes both writers, so the connection cannot be freed while it is + * selected. + */ +static struct ksmbd_conn *smb2_oplock_break_conn_get(struct oplock_info *opinfo, + struct ksmbd_inode *ci) +{ + struct ksmbd_conn *conn; + + down_read(&ci->m_lock); + conn = READ_ONCE(opinfo->conn); + if (conn && !ksmbd_conn_releasing(conn)) + conn = ksmbd_conn_get(conn); + else + conn = NULL; + up_read(&ci->m_lock); + + return conn; +} + /** * smb2_oplock_break_noti() - send smb2 exclusive/batch to level2 oplock * break command from server to client * @opinfo: oplock info object + * @ci: inode owning the break target's oplock list, pinned by + * the caller * * Return: 0 on success, otherwise error */ -static int smb2_oplock_break_noti(struct oplock_info *opinfo) +static int smb2_oplock_break_noti(struct oplock_info *opinfo, + struct ksmbd_inode *ci) { struct ksmbd_conn *conn; struct oplock_break_info *br_info; int ret = 0; struct ksmbd_work *work; - conn = READ_ONCE(opinfo->conn); + conn = smb2_oplock_break_conn_get(opinfo, ci); if (!conn) return ksmbd_invalidate_durable_fd(opinfo->fid); work = ksmbd_alloc_work_struct(); - if (!work) + if (!work) { + ksmbd_conn_put(conn); return -ENOMEM; + } br_info = kmalloc_obj(struct oplock_break_info, KSMBD_DEFAULT_GFP); if (!br_info) { ksmbd_free_work_struct(work); + ksmbd_conn_put(conn); return -ENOMEM; } @@ -957,7 +995,8 @@ static int smb2_oplock_break_noti(struct oplock_info *opinfo) br_info->open_trunc = opinfo->open_trunc; work->request_buf = (char *)br_info; - work->conn = ksmbd_conn_get(conn); + /* Transfer the reference acquired by smb2_oplock_break_conn_get(). */ + work->conn = conn; work->sess = opinfo->sess; ksmbd_conn_r_count_inc(conn); @@ -1154,9 +1193,9 @@ static void wait_lease_breaking(struct oplock_info *opinfo) } } -static int oplock_break(struct oplock_info *brk_opinfo, int req_op_level, - struct ksmbd_work *in_work, bool share_break, - bool sync_lease_break) +static int oplock_break(struct oplock_info *brk_opinfo, struct ksmbd_inode *ci, + int req_op_level, struct ksmbd_work *in_work, + bool share_break, bool sync_lease_break) { int err = 0; bool sent_interim = false; @@ -1298,7 +1337,7 @@ static int oplock_break(struct oplock_info *brk_opinfo, int req_op_level, } } - err = smb2_oplock_break_noti(brk_opinfo); + err = smb2_oplock_break_noti(brk_opinfo, ci); ksmbd_debug(OPLOCK, "oplock granted = %d\n", brk_opinfo->level); if (brk_opinfo->op_state == OPLOCK_CLOSING) @@ -1326,13 +1365,14 @@ static int oplock_break_add(struct list_head *head, struct oplock_info *opinfo) return 0; } -static void oplock_break_drain_none(struct list_head *head) +static void oplock_break_drain_none(struct list_head *head, + struct ksmbd_inode *ci) { struct oplock_break_entry *ent, *tmp; list_for_each_entry_safe(ent, tmp, head, list) { - oplock_break(ent->opinfo, SMB2_OPLOCK_LEVEL_NONE, NULL, false, - false); + oplock_break(ent->opinfo, ci, SMB2_OPLOCK_LEVEL_NONE, NULL, + false, false); list_del(&ent->list); opinfo_put(ent->opinfo); kfree(ent); @@ -1481,7 +1521,7 @@ void smb_send_parent_lease_break_noti(struct ksmbd_file *fp, } up_read(&p_ci->m_lock); - oplock_break_drain_none(&brk_list); + oplock_break_drain_none(&brk_list, p_ci); ksmbd_inode_put(p_ci); } @@ -1525,7 +1565,7 @@ void smb_lazy_parent_lease_break_close(struct ksmbd_file *fp) } up_read(&p_ci->m_lock); - oplock_break_drain_none(&brk_list); + oplock_break_drain_none(&brk_list, p_ci); ksmbd_inode_put(p_ci); } @@ -1665,7 +1705,7 @@ int smb_grant_oplock(struct ksmbd_work *work, int req_op_level, u64 pid, prev_durable_detached = prev_op_snapshot.durable_detached; prev_fid = prev_op_snapshot.fid; - err = oplock_break(prev_opinfo, break_level, work, + err = oplock_break(prev_opinfo, ci, break_level, work, share_ret < 0 && prev_opinfo->is_lease, false); if (prev_durable_detached || (prev_durable_open && err == -ENOENT)) ksmbd_invalidate_durable_fd(prev_fid); @@ -1771,7 +1811,8 @@ static bool smb_break_all_write_oplock(struct ksmbd_work *work, } brk_opinfo->open_trunc = is_trunc; - oplock_break(brk_opinfo, SMB2_OPLOCK_LEVEL_II, work, false, false); + oplock_break(brk_opinfo, fp->f_ci, SMB2_OPLOCK_LEVEL_II, work, false, + false); sent_break = true; opinfo_put(brk_opinfo); @@ -1863,7 +1904,7 @@ static void __smb_break_all_levII_oplock(struct ksmbd_work *work, brk_op->op_state = OPLOCK_STATE_NONE; spin_unlock(&brk_op->state_lock); } else { - oplock_break(brk_op, + oplock_break(brk_op, ci, brk_op->is_lease && !is_trunc ? SMB2_OPLOCK_LEVEL_II : SMB2_OPLOCK_LEVEL_NONE, send_interim && !sent_interim ? work : NULL, From 0480cee8cc3cc906124d398a9779eda144de6b41 Mon Sep 17 00:00:00 2001 From: Alon Shakevsky Date: Tue, 1 Sep 2026 00:05:31 +0000 Subject: [PATCH 3/4] ksmbd: validate COPYCHUNK source and target ranges ksmbd_vfs_copy_file_ranges() rejects negative source offsets in the copy loop, but it does not validate target offsets. It also calculates lock and overlap endpoints before ensuring that either range fits within MAX_LFS_FILESIZE. When the target is an alternate data stream, the buffered path passes a negative target offset to ksmbd_vfs_stream_write(). Let n be Length and let -d be TargetOffset, where 0 < d < n <= XATTR_SIZE_MAX. For an empty stream, the writer allocates n - d bytes, then copies n bytes starting d bytes before the allocation. An authenticated SMB client can control d and the source data, overwrite kernel heap memory, and crash the host. Validate both ranges before lock, overlap, or I/O calculations. Fixes: 8482150a0743 ("ksmbd: support copychunk for alternate data streams") Assisted-by: Antiproof:GPT-5.6-Sol Signed-off-by: Alon Shakevsky Signed-off-by: Namjae Jeon --- fs/smb/server/vfs.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c index d2b524f79cbe..c2c9aaa5de1b 100644 --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -2007,6 +2007,11 @@ static ssize_t ksmbd_vfs_copy_file_range_buffered(struct ksmbd_work *work, return ret; } +static bool ksmbd_vfs_copy_range_valid(loff_t offset, size_t len) +{ + return offset >= 0 && (loff_t)len <= MAX_LFS_FILESIZE - offset; +} + int ksmbd_vfs_copy_file_ranges(struct ksmbd_work *work, struct ksmbd_file *src_fp, struct ksmbd_file *dst_fp, @@ -2042,6 +2047,10 @@ int ksmbd_vfs_copy_file_ranges(struct ksmbd_work *work, dst_off = le64_to_cpu(chunks[i].TargetOffset); len = le32_to_cpu(chunks[i].Length); + if (!ksmbd_vfs_copy_range_valid(src_off, len) || + !ksmbd_vfs_copy_range_valid(dst_off, len)) + return -E2BIG; + if (check_lock_range(src_fp->filp, src_off, src_off + len - 1, READ)) return -EAGAIN; @@ -2134,7 +2143,8 @@ int ksmbd_vfs_copy_file_ranges(struct ksmbd_work *work, len = le32_to_cpu(chunks[i].Length); copy_len = len; - if (src_off < 0) + if (!ksmbd_vfs_copy_range_valid(src_off, len) || + !ksmbd_vfs_copy_range_valid(dst_off, len)) return -E2BIG; if (src_off > src_file_size || len > src_file_size - src_off) { From b5ec6c462aab1062cf5d1e667ba7c6442f737055 Mon Sep 17 00:00:00 2001 From: "Cen Zhang (Microsoft Security FORGE Labs)" Date: Tue, 1 Sep 2026 14:21:36 -0400 Subject: [PATCH 4/4] ksmbd: fix tree connection use-after-free in smb2_tree_connect() ksmbd_tree_conn_connect() publishes a new tree connection in sess->tree_conns with a single reference and returns its pointer to smb2_tree_connect(). The handler continues to initialize the object and build the response after publication. A concurrent session logoff can erase the connection and drop that reference, freeing the object while the handler still uses it. BUG: KASAN: slab-use-after-free in smb2_tree_connect+0xe3d/0xf90 smb2_tree_connect (fs/smb/server/smb2pdu.c:2872) handle_ksmbd_work process_one_work worker_thread kthread After xa_store() succeeds, take a second reference before releasing tree_conns_lock. The original reference belongs to the xarray entry and the second belongs to the creating smb2_tree_connect() handler. Keep the references balanced in every path: - On normal exit or an error after publication, smb2_tree_connect() drops its creator reference. Error cleanup also calls ksmbd_tree_conn_disconnect(), which drops the xarray reference only if it removes the exact entry. - SMB2 TREE_DISCONNECT uses the same helper to remove the entry and drop its xarray reference. The request's existing lookup reference remains owned by the request and is released by the existing cleanup. - Session LOGOFF removes each entry and drops its xarray reference. If it wins the race, later cleanup sees that the entry is gone and does not drop that reference again. To enforce this ownership, claim the disconnected state and erase the exact entry atomically under tree_conns_lock. This guarantees one drop for the xarray reference and one drop by each in-flight user, regardless of which teardown path wins. If logoff removes the entry before initialization completes, fail the connect instead of marking the detached object TREE_CONNECTED. Fixes: 33b235a6e6eb ("ksmbd: fix race condition between tree conn lookup and disconnect") Reported-by: Xiang Mei (Microsoft) Cc: AutonomousCodeSecurity@microsoft.com Cc: stable@vger.kernel.org Signed-off-by: Cen Zhang (Microsoft Security FORGE Labs) Signed-off-by: Namjae Jeon --- fs/smb/server/mgmt/tree_connect.c | 8 ++++++++ fs/smb/server/smb2pdu.c | 28 +++++++++++++--------------- 2 files changed, 21 insertions(+), 15 deletions(-) diff --git a/fs/smb/server/mgmt/tree_connect.c b/fs/smb/server/mgmt/tree_connect.c index 5f63e236267a..dd1db3554cae 100644 --- a/fs/smb/server/mgmt/tree_connect.c +++ b/fs/smb/server/mgmt/tree_connect.c @@ -82,6 +82,8 @@ ksmbd_tree_conn_connect(struct ksmbd_work *work, const char *share_name) down_write(&sess->tree_conns_lock); ret = xa_err(xa_store(&sess->tree_conns, tree_conn->id, tree_conn, KSMBD_DEFAULT_GFP)); + if (!ret) + atomic_inc(&tree_conn->refcount); up_write(&sess->tree_conns_lock); if (ret) { status.ret = -ENOMEM; @@ -129,6 +131,12 @@ int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, struct ksmbd_tree_connect *tree_conn) { down_write(&sess->tree_conns_lock); + if (tree_conn->t_state == TREE_DISCONNECTED || + xa_load(&sess->tree_conns, tree_conn->id) != tree_conn) { + up_write(&sess->tree_conns_lock); + return -ENOENT; + } + tree_conn->t_state = TREE_DISCONNECTED; xa_erase(&sess->tree_conns, tree_conn->id); up_write(&sess->tree_conns_lock); diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index d656832d82ef..0ecc52fde69c 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2790,6 +2790,7 @@ int smb2_tree_connect(struct ksmbd_work *work) struct ksmbd_session *sess = work->sess; char *treename = NULL, *name = NULL; struct ksmbd_tree_conn_status status; + struct ksmbd_tree_connect *tree_conn = NULL; struct ksmbd_share_config *share = NULL; int rc = -EINVAL; @@ -2817,6 +2818,7 @@ int smb2_tree_connect(struct ksmbd_work *work) status = ksmbd_tree_conn_connect(work, name); if (status.ret == KSMBD_TREE_CONN_STATUS_OK) { + tree_conn = status.tree_conn; rsp->hdr.Id.SyncId.TreeId = cpu_to_le32(status.tree_conn->id); share = status.tree_conn->share_conf; @@ -2860,8 +2862,15 @@ int smb2_tree_connect(struct ksmbd_work *work) status.tree_conn->posix_extensions = true; down_write(&sess->tree_conns_lock); - status.tree_conn->t_state = TREE_CONNECTED; + if (status.tree_conn->t_state == TREE_DISCONNECTED) { + status.ret = KSMBD_TREE_CONN_STATUS_ERROR; + share = NULL; + } else { + status.tree_conn->t_state = TREE_CONNECTED; + } up_write(&sess->tree_conns_lock); + if (status.ret != KSMBD_TREE_CONN_STATUS_OK) + goto out_err1; rsp->StructureSize = cpu_to_le16(16); out_err1: /* @@ -2888,9 +2897,6 @@ int smb2_tree_connect(struct ksmbd_work *work) rc = ksmbd_iov_pin_rsp(work, rsp, sizeof(struct smb2_tree_connect_rsp)); if (rc) { if (status.ret == KSMBD_TREE_CONN_STATUS_OK) { - down_write(&sess->tree_conns_lock); - status.tree_conn->t_state = TREE_DISCONNECTED; - up_write(&sess->tree_conns_lock); ksmbd_tree_conn_disconnect(sess, status.tree_conn); status.tree_conn = NULL; } @@ -2931,6 +2937,9 @@ int smb2_tree_connect(struct ksmbd_work *work) if (status.ret != KSMBD_TREE_CONN_STATUS_OK) smb2_set_err_rsp(work); + if (tree_conn) + ksmbd_tree_connect_put(tree_conn); + return rc; } @@ -3034,17 +3043,6 @@ int smb2_tree_disconnect(struct ksmbd_work *work) ksmbd_close_tree_conn_fds(work); - down_write(&sess->tree_conns_lock); - if (tcon->t_state == TREE_DISCONNECTED) { - up_write(&sess->tree_conns_lock); - rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED; - err = -ENOENT; - goto err_out; - } - - tcon->t_state = TREE_DISCONNECTED; - up_write(&sess->tree_conns_lock); - err = ksmbd_tree_conn_disconnect(sess, tcon); if (err) { rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED;