From b1e7cade3cafc593905f9ed81e7f6db3034eee1d Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Mon, 13 Jun 2022 06:32:44 +0100 Subject: [PATCH] io_uring: fix races with file table unregister [ Upstream commit b0380bf6dad4601d92025841e2b7a135d566c6e3 ] Fixed file 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: 05f3fb3c53975 ("io_uring: avoid ring quiesce for fixed file set unregister and update") Signed-off-by: Pavel Begunkov Signed-off-by: Sasha Levin --- fs/io_uring.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/io_uring.c b/fs/io_uring.c index b8e6398d9430..5f111a660fff 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7933,11 +7933,19 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx) static int io_sqe_files_unregister(struct io_ring_ctx *ctx) { + unsigned nr = ctx->nr_user_files; int ret; if (!ctx->file_data) return -ENXIO; + + /* + * Quiesce may unlock ->uring_lock, and while it's not held + * prevent new requests using the table. + */ + ctx->nr_user_files = 0; ret = io_rsrc_ref_quiesce(ctx->file_data, ctx); + ctx->nr_user_files = nr; if (!ret) __io_sqe_files_unregister(ctx); return ret;