2020-08-13 06:59:33

by Liu Yong

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

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 <[email protected]>
---
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

2020-08-13 14:57:45

by Jens Axboe

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

On 8/13/20 12:56 AM, Liu Yong wrote:
> 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.

Thanks, I'll add this for 5.4-stable, it doesn't affect any kernels newer
than that.

--
Jens Axboe