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@xxxxxx>
---
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)
--
2.30.2
