Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 358 insertions, 0 deletions

diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
new file mode 100644
index 000000000..3067c9343
--- /dev/null
+++ b/io_uring/msg_ring.c
@@ -0,0 +1,358 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/nospec.h>
+#include <linux/io_uring.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "io_uring.h"
+#include "rsrc.h"
+#include "filetable.h"
+#include "msg_ring.h"
+
+/* All valid masks for MSG_RING */
+#define IORING_MSG_RING_MASK		(IORING_MSG_RING_CQE_SKIP | \
+					IORING_MSG_RING_FLAGS_PASS)
+
+struct io_msg {
+	struct file			*file;
+	struct file			*src_file;
+	struct callback_head		tw;
+	u64 user_data;
+	u32 len;
+	u32 cmd;
+	u32 src_fd;
+	union {
+		u32 dst_fd;
+		u32 cqe_flags;
+	};
+	u32 flags;
+};
+
+static void io_double_unlock_ctx(struct io_ring_ctx *octx)
+{
+	mutex_unlock(&octx->uring_lock);
+}
+
+static int io_lock_external_ctx(struct io_ring_ctx *octx,
+				unsigned int issue_flags)
+{
+	/*
+	 * To ensure proper ordering between the two ctxs, we can only
+	 * attempt a trylock on the target. If that fails and we already have
+	 * the source ctx lock, punt to io-wq.
+	 */
+	if (!(issue_flags & IO_URING_F_UNLOCKED)) {
+		if (!mutex_trylock(&octx->uring_lock))
+			return -EAGAIN;
+		return 0;
+	}
+	mutex_lock(&octx->uring_lock);
+	return 0;
+}
+
+void io_msg_ring_cleanup(struct io_kiocb *req)
+{
+	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+
+	if (WARN_ON_ONCE(!msg->src_file))
+		return;
+
+	fput(msg->src_file);
+	msg->src_file = NULL;
+}
+
+static inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx)
+{
+	return target_ctx->int_flags & IO_RING_F_TASK_COMPLETE;
+}
+
+static void io_msg_tw_complete(struct io_tw_req tw_req, io_tw_token_t tw)
+{
+	struct io_kiocb *req = tw_req.req;
+	struct io_ring_ctx *ctx = req->ctx;
+
+	io_add_aux_cqe(ctx, req->cqe.user_data, req->cqe.res, req->cqe.flags);
+	kfree_rcu(req, rcu_head);
+	percpu_ref_put(&ctx->refs);
+}
+
+static void io_msg_remote_post(struct io_ring_ctx *ctx, struct io_kiocb *req,
+			      int res, u32 cflags, u64 user_data)
+{
+	req->opcode = IORING_OP_NOP;
+	req->cqe.user_data = user_data;
+	io_req_set_res(req, res, cflags);
+	percpu_ref_get(&ctx->refs);
+	req->ctx = ctx;
+	req->tctx = NULL;
+	req->io_task_work.func = io_msg_tw_complete;
+	io_req_task_work_add_remote(req, IOU_F_TWQ_LAZY_WAKE);
+}
+
+static int io_msg_ring_cqe_flags(struct io_ring_ctx *target_ctx,
+				 const struct io_msg *msg, u32 *flags)
+{
+	*flags = 0;
+
+	if (!(msg->flags & IORING_MSG_RING_FLAGS_PASS))
+		return 0;
+
+	*flags = msg->cqe_flags;
+	if ((*flags & IORING_CQE_F_32) &&
+	    !(target_ctx->flags & (IORING_SETUP_CQE32 |
+				   IORING_SETUP_CQE_MIXED)))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int io_msg_data_remote(struct io_ring_ctx *target_ctx,
+			      struct io_msg *msg)
+{
+	struct io_kiocb *target;
+	u32 flags;
+	int ret;
+
+	ret = io_msg_ring_cqe_flags(target_ctx, msg, &flags);
+	if (ret)
+		return ret;
+
+	target = kmem_cache_alloc(req_cachep, GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO);
+	if (unlikely(!target))
+		return -ENOMEM;
+
+	io_msg_remote_post(target_ctx, target, msg->len, flags, msg->user_data);
+	return 0;
+}
+
+static int __io_msg_ring_data(struct io_ring_ctx *target_ctx,
+			      struct io_msg *msg, unsigned int issue_flags)
+{
+	u32 flags = 0;
+	int ret;
+
+	if (msg->src_fd || msg->flags & ~IORING_MSG_RING_FLAGS_PASS)
+		return -EINVAL;
+	if (!(msg->flags & IORING_MSG_RING_FLAGS_PASS) && msg->dst_fd)
+		return -EINVAL;
+	/*
+	 * Keep IORING_SETUP_R_DISABLED check before submitter_task load
+	 * in io_msg_data_remote() -> io_req_task_work_add_remote()
+	 */
+	if (smp_load_acquire(&target_ctx->flags) & IORING_SETUP_R_DISABLED)
+		return -EBADFD;
+
+	if (io_msg_need_remote(target_ctx))
+		return io_msg_data_remote(target_ctx, msg);
+
+	ret = io_msg_ring_cqe_flags(target_ctx, msg, &flags);
+	if (ret)
+		return ret;
+
+	ret = -EOVERFLOW;
+	if (target_ctx->flags & IORING_SETUP_IOPOLL) {
+		if (unlikely(io_lock_external_ctx(target_ctx, issue_flags)))
+			return -EAGAIN;
+	}
+	if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
+		ret = 0;
+	if (target_ctx->flags & IORING_SETUP_IOPOLL)
+		io_double_unlock_ctx(target_ctx);
+	return ret;
+}
+
+static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *target_ctx = req->file->private_data;
+	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+
+	return __io_msg_ring_data(target_ctx, msg, issue_flags);
+}
+
+static int io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_rsrc_node *node;
+	int ret = -EBADF;
+
+	io_ring_submit_lock(ctx, issue_flags);
+	node = io_rsrc_node_lookup(&ctx->file_table.data, msg->src_fd);
+	if (node) {
+		msg->src_file = io_slot_file(node);
+		if (msg->src_file)
+			get_file(msg->src_file);
+		req->flags |= REQ_F_NEED_CLEANUP;
+		ret = 0;
+	}
+	io_ring_submit_unlock(ctx, issue_flags);
+	return ret;
+}
+
+static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *target_ctx = req->file->private_data;
+	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+	struct file *src_file = msg->src_file;
+	int ret;
+
+	if (unlikely(io_lock_external_ctx(target_ctx, issue_flags)))
+		return -EAGAIN;
+
+	ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd);
+	if (ret < 0)
+		goto out_unlock;
+
+	msg->src_file = NULL;
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+
+	if (msg->flags & IORING_MSG_RING_CQE_SKIP)
+		goto out_unlock;
+	/*
+	 * If this fails, the target still received the file descriptor but
+	 * wasn't notified of the fact. This means that if this request
+	 * completes with -EOVERFLOW, then the sender must ensure that a
+	 * later IORING_OP_MSG_RING delivers the message.
+	 */
+	if (!io_post_aux_cqe(target_ctx, msg->user_data, ret, 0))
+		ret = -EOVERFLOW;
+out_unlock:
+	io_double_unlock_ctx(target_ctx);
+	return ret;
+}
+
+static void io_msg_tw_fd_complete(struct callback_head *head)
+{
+	struct io_msg *msg = container_of(head, struct io_msg, tw);
+	struct io_kiocb *req = cmd_to_io_kiocb(msg);
+	int ret = -EOWNERDEAD;
+
+	if (!(current->flags & PF_EXITING))
+		ret = io_msg_install_complete(req, IO_URING_F_UNLOCKED);
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_queue_tw_complete(req, ret);
+}
+
+static int io_msg_fd_remote(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->file->private_data;
+	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+	struct task_struct *task = ctx->submitter_task;
+
+	init_task_work(&msg->tw, io_msg_tw_fd_complete);
+	if (task_work_add(task, &msg->tw, TWA_SIGNAL))
+		return -EOWNERDEAD;
+
+	return IOU_ISSUE_SKIP_COMPLETE;
+}
+
+static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *target_ctx = req->file->private_data;
+	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (msg->len)
+		return -EINVAL;
+	if (target_ctx == ctx)
+		return -EINVAL;
+	/*
+	 * Keep IORING_SETUP_R_DISABLED check before submitter_task load
+	 * in io_msg_fd_remote()
+	 */
+	if (smp_load_acquire(&target_ctx->flags) & IORING_SETUP_R_DISABLED)
+		return -EBADFD;
+	if (!msg->src_file) {
+		int ret = io_msg_grab_file(req, issue_flags);
+		if (unlikely(ret))
+			return ret;
+	}
+
+	if (io_msg_need_remote(target_ctx))
+		return io_msg_fd_remote(req);
+	return io_msg_install_complete(req, issue_flags);
+}
+
+static int __io_msg_ring_prep(struct io_msg *msg, const struct io_uring_sqe *sqe)
+{
+	if (unlikely(sqe->buf_index || sqe->personality))
+		return -EINVAL;
+
+	msg->src_file = NULL;
+	msg->user_data = READ_ONCE(sqe->off);
+	msg->len = READ_ONCE(sqe->len);
+	msg->cmd = READ_ONCE(sqe->addr);
+	msg->src_fd = READ_ONCE(sqe->addr3);
+	msg->dst_fd = READ_ONCE(sqe->file_index);
+	msg->flags = READ_ONCE(sqe->msg_ring_flags);
+	if (msg->flags & ~IORING_MSG_RING_MASK)
+		return -EINVAL;
+
+	return 0;
+}
+
+int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return __io_msg_ring_prep(io_kiocb_to_cmd(req, struct io_msg), sqe);
+}
+
+int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+	int ret;
+
+	ret = -EBADFD;
+	if (!io_is_uring_fops(req->file))
+		goto done;
+
+	switch (msg->cmd) {
+	case IORING_MSG_DATA:
+		ret = io_msg_ring_data(req, issue_flags);
+		break;
+	case IORING_MSG_SEND_FD:
+		ret = io_msg_send_fd(req, issue_flags);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+done:
+	if (ret < 0) {
+		if (ret == -EAGAIN || ret == IOU_ISSUE_SKIP_COMPLETE)
+			return ret;
+		req_set_fail(req);
+	}
+	io_req_set_res(req, ret, 0);
+	return IOU_COMPLETE;
+}
+
+int io_uring_sync_msg_ring(struct io_uring_sqe *sqe)
+{
+	struct io_msg io_msg = { };
+	int ret;
+
+	ret = __io_msg_ring_prep(&io_msg, sqe);
+	if (unlikely(ret))
+		return ret;
+
+	/*
+	 * Only data sending supported, not IORING_MSG_SEND_FD as that one
+	 * doesn't make sense without a source ring to send files from.
+	 */
+	if (io_msg.cmd != IORING_MSG_DATA)
+		return -EINVAL;
+
+	CLASS(fd, f)(sqe->fd);
+	if (fd_empty(f))
+		return -EBADF;
+	if (!io_is_uring_fops(fd_file(f)))
+		return -EBADFD;
+	return  __io_msg_ring_data(fd_file(f)->private_data,
+				   &io_msg, IO_URING_F_UNLOCKED);
+}