6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Namjae Jeon [ Upstream commit 215e8816b1ac25176d911abb8704390413ccee4b ] A file_lock retained by ksmbd for byte-range lock bookkeeping can still be part of the VFS blocked-request graph. In particular, the VFS can chain a new waiter below an already blocked request through flc_blocked_requests. The ksmbd_file reference count does not cover that graph. Both __ksmbd_close_fd() and the cross-request unlock path free these retained file_lock objects directly. If a dependent waiter is still attached, locks_release_private() hits BUG_ON(!list_empty(&flc->flc_blocked_requests)). The same lifetime mismatch can leave a freed ksmbd_lock reachable through its request-local llist. Detach the file_lock from the blocked-request graph before freeing it in the close, cross-request unlock, and rollback paths. locks_delete_block() also wakes requests chained below the object. Remove llist when a completed lock is published so a globally visible ksmbd_lock no longer points into the submitting worker's stack. Fixes: d63528eb0d43 ("ksmbd: free ksmbd_lock when file is closed") Reported-by: Kyenghwan Hwang Tested-by: Kyenghwan Hwang Tested-by: ChenXiaoSong Reviewed-by: ChenXiaoSong Signed-off-by: Namjae Jeon Signed-off-by: Sasha Levin --- fs/smb/server/smb2pdu.c | 14 ++++++++++---- fs/smb/server/vfs_cache.c | 8 +++++--- 2 files changed, 15 insertions(+), 7 deletions(-) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 0785f921aec06..b2d4c30571d6c 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -7524,6 +7524,12 @@ static void smb2_remove_blocked_lock(void **argv) locks_wake_up(flock); } +static void smb2_free_lock(struct file_lock *flock) +{ + ksmbd_vfs_posix_lock_unblock(flock); + locks_free_lock(flock); +} + static inline bool lock_defer_pending(struct file_lock *fl) { /* check pending lock waiters */ @@ -7677,14 +7683,14 @@ int smb2_lock(struct ksmbd_work *work) cmp_lock->end == smb_lock->end && !lock_defer_pending(cmp_lock->fl)) { nolock = 0; - list_del(&cmp_lock->flist); - list_del(&cmp_lock->clist); + list_del_init(&cmp_lock->flist); + list_del_init(&cmp_lock->clist); cmp_lock->conn = NULL; spin_unlock(&conn->llist_lock); up_read(&conn_list_lock); ksmbd_conn_put(conn); - locks_free_lock(cmp_lock->fl); + smb2_free_lock(cmp_lock->fl); kfree(cmp_lock); goto out_check_cl; } @@ -7882,7 +7888,7 @@ int smb2_lock(struct ksmbd_work *work) spin_unlock(&conn->llist_lock); ksmbd_conn_put(conn); - locks_free_lock(smb_lock->fl); + smb2_free_lock(smb_lock->fl); if (rlock) locks_free_lock(rlock); kfree(smb_lock); diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c index ce6e9886df8be..970b8f185aacd 100644 --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -388,8 +388,9 @@ static void __ksmbd_close_fd(struct ksmbd_file_table *ft, struct ksmbd_file *fp) if (!IS_ERR_OR_NULL(filp)) fput(filp); - /* because the reference count of fp is 0, it is guaranteed that - * there are not accesses to fp->lock_list. + /* + * The zero fp reference count serializes access to fp->lock_list, but + * the VFS may still have blocked requests chained below these locks. */ list_for_each_entry_safe(smb_lock, tmp_lock, &fp->lock_list, flist) { struct ksmbd_conn *conn = smb_lock->conn; @@ -402,7 +403,8 @@ static void __ksmbd_close_fd(struct ksmbd_file_table *ft, struct ksmbd_file *fp) ksmbd_conn_put(conn); } - list_del(&smb_lock->flist); + list_del_init(&smb_lock->flist); + ksmbd_vfs_posix_lock_unblock(smb_lock->fl); locks_free_lock(smb_lock->fl); kfree(smb_lock); } -- 2.53.0