Commit 9e15c3a0 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: convert io_buffer_idr to XArray 



Like we did for the personality idr, convert the IO buffer idr to use
XArray. This avoids a use-after-free on removal of entries, since idr
doesn't like doing so from inside an iterator, and it nicely reduces
the amount of code we need to support this feature.

Fixes: 5a2e745d ("io_uring: buffer registration infrastructure")
Cc: stable@vger.kernel.org
Cc: Matthew Wilcox <willy@infradead.org>
Cc: yangerkun <yangerkun@huawei.com>
Reported-by: default avatarHulk Robot <hulkci@huawei.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 16efa4fc

fs/io_uring.c

+15 −28
Original line number Diff line number Diff line
@@ -402,7 +402,7 @@ struct io_ring_ctx { 
	struct socket		*ring_sock;

#endif



	struct idr		io_buffer_idr;

	struct xarray		io_buffers;



	struct xarray		personalities;

	u32			pers_next;
@@ -1135,7 +1135,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) 
	init_waitqueue_head(&ctx->cq_wait);

	INIT_LIST_HEAD(&ctx->cq_overflow_list);

	init_completion(&ctx->ref_comp);

	idr_init(&ctx->io_buffer_idr);

	xa_init_flags(&ctx->io_buffers, XA_FLAGS_ALLOC1);

	xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);

	mutex_init(&ctx->uring_lock);

	init_waitqueue_head(&ctx->wait);
@@ -2843,7 +2843,7 @@ static struct io_buffer *io_buffer_select(struct io_kiocb *req, size_t *len, 


	lockdep_assert_held(&req->ctx->uring_lock);



	head = idr_find(&req->ctx->io_buffer_idr, bgid);

	head = xa_load(&req->ctx->io_buffers, bgid);

	if (head) {

		if (!list_empty(&head->list)) {

			kbuf = list_last_entry(&head->list, struct io_buffer,
@@ -2851,7 +2851,7 @@ static struct io_buffer *io_buffer_select(struct io_kiocb *req, size_t *len, 
			list_del(&kbuf->list);

		} else {

			kbuf = head;

			idr_remove(&req->ctx->io_buffer_idr, bgid);

			xa_erase(&req->ctx->io_buffers, bgid);

		}

		if (*len > kbuf->len)

			*len = kbuf->len;
@@ -3892,7 +3892,7 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx, struct io_buffer *buf, 
	}

	i++;

	kfree(buf);

	idr_remove(&ctx->io_buffer_idr, bgid);

	xa_erase(&ctx->io_buffers, bgid);



	return i;

}
@@ -3910,7 +3910,7 @@ static int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags) 
	lockdep_assert_held(&ctx->uring_lock);



	ret = -ENOENT;

	head = idr_find(&ctx->io_buffer_idr, p->bgid);

	head = xa_load(&ctx->io_buffers, p->bgid);

	if (head)

		ret = __io_remove_buffers(ctx, head, p->bgid, p->nbufs);

	if (ret < 0)
@@ -3993,21 +3993,14 @@ static int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags) 


	lockdep_assert_held(&ctx->uring_lock);



	list = head = idr_find(&ctx->io_buffer_idr, p->bgid);

	list = head = xa_load(&ctx->io_buffers, p->bgid);



	ret = io_add_buffers(p, &head);

	if (ret >= 0 && !list) {

		ret = xa_insert(&ctx->io_buffers, p->bgid, head, GFP_KERNEL);

		if (ret < 0)

		goto out;



	if (!list) {

		ret = idr_alloc(&ctx->io_buffer_idr, head, p->bgid, p->bgid + 1,

					GFP_KERNEL);

		if (ret < 0) {

			__io_remove_buffers(ctx, head, p->bgid, -1U);

			goto out;

		}

	}

out:

	if (ret < 0)

		req_set_fail_links(req);
@@ -8333,19 +8326,13 @@ static int io_eventfd_unregister(struct io_ring_ctx *ctx) 
	return -ENXIO;

}



static int __io_destroy_buffers(int id, void *p, void *data)

{

	struct io_ring_ctx *ctx = data;

	struct io_buffer *buf = p;



	__io_remove_buffers(ctx, buf, id, -1U);

	return 0;

}



static void io_destroy_buffers(struct io_ring_ctx *ctx)

{

	idr_for_each(&ctx->io_buffer_idr, __io_destroy_buffers, ctx);

	idr_destroy(&ctx->io_buffer_idr);

	struct io_buffer *buf;

	unsigned long index;



	xa_for_each(&ctx->io_buffers, index, buf)

		__io_remove_buffers(ctx, buf, index, -1U);

}



static void io_req_cache_free(struct list_head *list, struct task_struct *tsk)