| From 4b2ba4c9b8148563592663f341474355e3fe444a Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 13 Jun 2022 06:30:06 +0100 |
| Subject: io_uring: fix races with buffer table unregister |
| |
| From: Pavel Begunkov <asml.silence@gmail.com> |
| |
| [ Upstream commit d11d31fc5d8a96f707facee0babdcffaafa38de2 ] |
| |
| Fixed buffer table quiesce might unlock ->uring_lock, potentially |
| letting new requests to be submitted, don't allow those requests to |
| use the table as they will race with unregistration. |
| |
| Reported-and-tested-by: van fantasy <g1042620637@gmail.com> |
| Fixes: bd54b6fe3316ec ("io_uring: implement fixed buffers registration similar to fixed files") |
| Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| fs/io_uring.c | 7 +++++++ |
| 1 file changed, 7 insertions(+) |
| |
| diff --git a/fs/io_uring.c b/fs/io_uring.c |
| index 0a9f9000fc80..3d123ca028c9 100644 |
| --- a/fs/io_uring.c |
| +++ b/fs/io_uring.c |
| @@ -9495,12 +9495,19 @@ static void __io_sqe_buffers_unregister(struct io_ring_ctx *ctx) |
| |
| static int io_sqe_buffers_unregister(struct io_ring_ctx *ctx) |
| { |
| + unsigned nr = ctx->nr_user_bufs; |
| int ret; |
| |
| if (!ctx->buf_data) |
| return -ENXIO; |
| |
| + /* |
| + * Quiesce may unlock ->uring_lock, and while it's not held |
| + * prevent new requests using the table. |
| + */ |
| + ctx->nr_user_bufs = 0; |
| ret = io_rsrc_ref_quiesce(ctx->buf_data, ctx); |
| + ctx->nr_user_bufs = nr; |
| if (!ret) |
| __io_sqe_buffers_unregister(ctx); |
| return ret; |
| -- |
| 2.35.1 |
| |
