io_uring: fix no lock protection for ctx->cq_extra

[ Upstream commit e302f1046f4c209291b07ff7bc4d15ca26891f16 ]

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

Cc: stable@vger.kernel.org
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20211125092103.224502-2-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index d7e49e8..156c54e 100644 (file)
--- 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 */