Commit f9437ac0 authored Jun 13, 2022 by Dylan Yudaken Committed by Jens Axboe Jun 13, 2022

io_uring: limit size of provided buffer ring



The type of head and tail do not allow more than 2^15 entries in a
provided buffer ring, so do not allow this.
At 2^16 while each entry can be indexed, there is no way to
disambiguate full vs empty.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220613101157.3687-4-dylany@fb.com


Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent c6e9fa5c

fs/io_uring.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -13002,6 +13002,10 @@ static int io_register_pbuf_ring(struct io_ring_ctx ctx, void __user arg)
		if (!is_power_of_2(reg.ring_entries))
		return -EINVAL;

		/* cannot disambiguate full vs empty due to head/tail size */
		if (reg.ring_entries >= 65536)
		return -EINVAL;

		if (unlikely(reg.bgid < BGID_ARRAY && !ctx->io_bl)) {
		int ret = io_init_bl_list(ctx);
		if (ret)