From d11d31fc5d8a96f707facee0babdcffaafa38de2 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Mon, 13 Jun 2022 06:30:06 +0100 Subject: [PATCH] io_uring: fix races with buffer table unregister 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 Fixes: bd54b6fe3316ec ("io_uring: implement fixed buffers registration similar to fixed files") Signed-off-by: Pavel Begunkov --- fs/io_uring.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/io_uring.c b/fs/io_uring.c index 00d2667..be05f37 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -10680,12 +10680,19 @@ 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; -- 2.7.4