Fwd: [PATCH] fs/io_uring.c: Fix uninitialized variable is referenced in io_submit_sqe

[Jens Axboe <axboe@kernel.dk>]

Hi,

Can you queue this up for 5.4 as well? Thanks!


-------- Forwarded Message --------
Subject: [PATCH] fs/io_uring.c: Fix uninitialized variable is referenced in io_submit_sqe
Date: Wed, 12 Aug 2020 23:56:44 -0700
From: Liu Yong <pkfxxxing@gmail.com>
To: Jens Axboe <axboe@kernel.dk>
CC: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org

the commit <a4d61e66ee4a> ("<io_uring: prevent re-read of sqe->opcode>") 
caused another vulnerability. After io_get_req(), the sqe_submit struct 
in req is not initialized, but the following code defaults that 
req->submit.opcode is available.

Signed-off-by: Liu Yong <pkfxxxing@gmail.com>
---
 fs/io_uring.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index be3d595a607f..c1aaee061dae 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2559,6 +2559,7 @@ static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
 		goto err;
 	}
 
+	memcpy(&req->submit, s, sizeof(*s));
 	ret = io_req_set_file(ctx, s, state, req);
 	if (unlikely(ret)) {
 err_req:
-- 
2.17.1