From f9437ac0f851cea2374d53594f52fbbefdd977bd Mon Sep 17 00:00:00 2001
From: Dylan Yudaken <dylany@fb.com>
Date: Mon, 13 Jun 2022 03:11:57 -0700
Subject: [PATCH] io_uring: limit size of provided buffer ring
Git-commit: f9437ac0f851cea2374d53594f52fbbefdd977bd
Patch-mainline: v5.19-rc3
References: bsc#1205205
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>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
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)
--
2.35.3