io_uring-6.6-2023-10-06

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Merge tag 'io_uring-6.6-2023-10-06' of git://git.kernel.dk/linux

Pull io_uring fixes from Jens Axboe:

 - syzbot report on a crash on 32-bit arm with highmem, and went digging
   to check for potentially similar issues and found one more (me)

 - Fix a syzbot report with PROVE_LOCKING=y and setting up the ring in a
   disabled state (me)

 - Fix for race with CPU hotplut and io-wq init (Jeff)

* tag 'io_uring-6.6-2023-10-06' of git://git.kernel.dk/linux:
  io-wq: fully initialize wqe before calling cpuhp_state_add_instance_nocalls()
  io_uring: don't allow IORING_SETUP_NO_MMAP rings on highmem pages
  io_uring: ensure io_lockdep_assert_cq_locked() handles disabled rings
  io_uring/kbuf: don't allow registered buffer rings on highmem pages

io_uring/io-wq.c

@@ -1151,9 +1151,6 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 	wq = kzalloc(sizeof(struct io_wq), GFP_KERNEL);
 	if (!wq)
 		return ERR_PTR(-ENOMEM);
-	ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
-	if (ret)
-		goto err_wq;
 
 	refcount_inc(&data->hash->refs);
 	wq->hash = data->hash;
@@ -1186,13 +1183,14 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 	wq->task = get_task_struct(data->task);
 	atomic_set(&wq->worker_refs, 1);
 	init_completion(&wq->worker_done);
+	ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
+	if (ret)
+		goto err;
+
 	return wq;
 err:
 	io_wq_put_hash(data->hash);
-	cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
-
 	free_cpumask_var(wq->cpu_mask);
-err_wq:
 	kfree(wq);
 	return ERR_PTR(ret);
 }

io_uring/io_uring.c

@@ -2686,7 +2686,7 @@ static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
 {
 	struct page **page_array;
 	unsigned int nr_pages;
-	int ret;
+	int ret, i;
 
 	*npages = 0;
 
@@ -2716,6 +2716,20 @@ static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
 	 */
 	if (page_array[0] != page_array[ret - 1])
 		goto err;
+
+	/*
+	 * Can't support mapping user allocated ring memory on 32-bit archs
+	 * where it could potentially reside in highmem. Just fail those with
+	 * -EINVAL, just like we did on kernels that didn't support this
+	 * feature.
+	 */
+	for (i = 0; i < nr_pages; i++) {
+		if (PageHighMem(page_array[i])) {
+			ret = -EINVAL;
+			goto err;
+		}
+	}
+
 	*pages = page_array;
 	*npages = nr_pages;
 	return page_to_virt(page_array[0]);

io_uring/io_uring.h

@@ -86,20 +86,33 @@ bool __io_alloc_req_refill(struct io_ring_ctx *ctx);
 bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task,
 			bool cancel_all);
 
-#define io_lockdep_assert_cq_locked(ctx)				\
+#if defined(CONFIG_PROVE_LOCKING)
-	do {								\
+static inline void io_lockdep_assert_cq_locked(struct io_ring_ctx *ctx)
-		lockdep_assert(in_task());				\
+{
-									\
+	lockdep_assert(in_task());
-		if (ctx->flags & IORING_SETUP_IOPOLL) {			\
+
-			lockdep_assert_held(&ctx->uring_lock);		\
+	if (ctx->flags & IORING_SETUP_IOPOLL) {
-		} else if (!ctx->task_complete) {			\
+		lockdep_assert_held(&ctx->uring_lock);
-			lockdep_assert_held(&ctx->completion_lock);	\
+	} else if (!ctx->task_complete) {
-		} else if (ctx->submitter_task->flags & PF_EXITING) {	\
+		lockdep_assert_held(&ctx->completion_lock);
-			lockdep_assert(current_work());			\
+	} else if (ctx->submitter_task) {
-		} else {						\
+		/*
-			lockdep_assert(current == ctx->submitter_task);	\
+		 * ->submitter_task may be NULL and we can still post a CQE,
-		}							\
+		 * if the ring has been setup with IORING_SETUP_R_DISABLED.
-	} while (0)
+		 * Not from an SQE, as those cannot be submitted, but via
+		 * updating tagged resources.
+		 */
+		if (ctx->submitter_task->flags & PF_EXITING)
+			lockdep_assert(current_work());
+		else
+			lockdep_assert(current == ctx->submitter_task);
+	}
+}
+#else
+static inline void io_lockdep_assert_cq_locked(struct io_ring_ctx *ctx)
+{
+}
+#endif
 
 static inline void io_req_task_work_add(struct io_kiocb *req)
 {

io_uring/kbuf.c

@@ -477,7 +477,7 @@ static int io_pin_pbuf_ring(struct io_uring_buf_reg *reg,
 {
 	struct io_uring_buf_ring *br;
 	struct page **pages;
-	int nr_pages;
+	int i, nr_pages;
 
 	pages = io_pin_pages(reg->ring_addr,
 			     flex_array_size(br, bufs, reg->ring_entries),
@@ -485,6 +485,17 @@ static int io_pin_pbuf_ring(struct io_uring_buf_reg *reg,
 	if (IS_ERR(pages))
 		return PTR_ERR(pages);
 
+	/*
+	 * Apparently some 32-bit boxes (ARM) will return highmem pages,
+	 * which then need to be mapped. We could support that, but it'd
+	 * complicate the code and slowdown the common cases quite a bit.
+	 * So just error out, returning -EINVAL just like we did on kernels
+	 * that didn't support mapped buffer rings.
+	 */
+	for (i = 0; i < nr_pages; i++)
+		if (PageHighMem(pages[i]))
+			goto error_unpin;
+
 	br = page_address(pages[0]);
 #ifdef SHM_COLOUR
 	/*
@@ -496,13 +507,8 @@ static int io_pin_pbuf_ring(struct io_uring_buf_reg *reg,
 	 * should use IOU_PBUF_RING_MMAP instead, and liburing will handle
 	 * this transparently.
 	 */
-	if ((reg->ring_addr | (unsigned long) br) & (SHM_COLOUR - 1)) {
+	if ((reg->ring_addr | (unsigned long) br) & (SHM_COLOUR - 1))
-		int i;
+		goto error_unpin;
-
-		for (i = 0; i < nr_pages; i++)
-			unpin_user_page(pages[i]);
-		return -EINVAL;
-	}
 #endif
 	bl->buf_pages = pages;
 	bl->buf_nr_pages = nr_pages;
@@ -510,6 +516,11 @@ static int io_pin_pbuf_ring(struct io_uring_buf_reg *reg,
 	bl->is_mapped = 1;
 	bl->is_mmap = 0;
 	return 0;
+error_unpin:
+	for (i = 0; i < nr_pages; i++)
+		unpin_user_page(pages[i]);
+	kvfree(pages);
+	return -EINVAL;
 }
 
 static int io_alloc_pbuf_ring(struct io_uring_buf_reg *reg,