linux-kernel - [PATCH 5.15 045/262] io_uring: fix no lock protection for ctx->cq

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Date:   Mon,  7 Mar 2022 10:16:29 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hao Xu <haoxu@...ux.alibaba.com>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 045/262] io_uring: fix no lock protection for ctx->cq_extra

From: Hao Xu <haoxu@...ux.alibaba.com>

[ Upstream commit e302f1046f4c209291b07ff7bc4d15ca26891f16 ]

ctx->cq_extra should be protected by completion lock so that the
req_need_defer() does the right check.

Cc: stable@...r.kernel.org
Signed-off-by: Hao Xu <haoxu@...ux.alibaba.com>
Link: https://lore.kernel.org/r/20211125092103.224502-2-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/io_uring.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index d7e49e87b49b9..156c54ebb62b7 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6573,11 +6573,14 @@ static bool io_drain_req(struct io_kiocb *req)
 	}
 
 	/* Still need defer if there is pending req in defer list. */
+	spin_lock(&ctx->completion_lock);
 	if (likely(list_empty_careful(&ctx->defer_list) &&
 		!(req->flags & REQ_F_IO_DRAIN))) {
+		spin_unlock(&ctx->completion_lock);
 		ctx->drain_active = false;
 		return false;
 	}
+	spin_unlock(&ctx->completion_lock);
 
 	seq = io_get_sequence(req);
 	/* Still a chance to pass the sequence check */
-- 
2.34.1