From f9437ac0f851cea2374d53594f52fbbefdd977bd Mon Sep 17 00:00:00 2001 From: Dylan Yudaken Date: Mon, 13 Jun 2022 03:11:57 -0700 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/20220613101157.3687-4-dylany@fb.com Reviewed-by: Hao Xu Signed-off-by: Jens Axboe --- fs/io_uring.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/io_uring.c b/fs/io_uring.c index 6eea18e8330c..85b116ddfd2a 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -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)