[PATCH 1/3] io_uring: fix index calculation

[Dylan Yudaken <dylany@fb.com>]

When indexing into a provided buffer ring, do not subtract 1 from the
index.

Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
---
 fs/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3aab4182fd89..9cf9aff51b70 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3888,7 +3888,7 @@ static void __user *io_ring_buffer_select(struct io_kiocb *req, size_t *len,
 		buf = &br->bufs[head];
 	} else {
 		int off = head & (IO_BUFFER_LIST_BUF_PER_PAGE - 1);
-		int index = head / IO_BUFFER_LIST_BUF_PER_PAGE - 1;
+		int index = head / IO_BUFFER_LIST_BUF_PER_PAGE;
 		buf = page_address(bl->buf_pages[index]);
 		buf += off;
 	}
-- 
2.30.2