From b0380bf6dad4601d92025841e2b7a135d566c6e3 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Mon, 13 Jun 2022 06:32:44 +0100
Subject: [PATCH] io_uring: fix races with file table unregister
Git-commit: b0380bf6dad4601d92025841e2b7a135d566c6e3
Patch-mainline: v5.19-rc3
References: bsc#1205205
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 <g1042620637@gmail.com>
Fixes: 05f3fb3c53975 ("io_uring: avoid ring quiesce for fixed file set unregister and update")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
fs/io_uring.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index ed3416a7b2e9..00d266746916 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9768,11 +9768,19 @@ 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;
--
2.35.3