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authorDylan Yudaken <dylany@meta.com>2023-01-27 02:59:11 -0800
committerJens Axboe <axboe@kernel.dk>2023-01-27 06:29:29 -0700
commitef5c600adb1d985513d2b612cc90403a148ff287 (patch)
tree940c64ade39062e269766cab91a7b9b55bccf32a
parentb00c51ef8f72ced0965d021a291b98ff822c5337 (diff)
downloadlinux-ef5c600adb1d985513d2b612cc90403a148ff287.tar.bz2
io_uring: always prep_async for drain requests
Drain requests all go through io_drain_req, which has a quick exit in case there is nothing pending (ie the drain is not useful). In that case it can run the issue the request immediately. However for safety it queues it through task work. The problem is that in this case the request is run asynchronously, but the async work has not been prepared through io_req_prep_async. This has not been a problem up to now, as the task work always would run before returning to userspace, and so the user would not have a chance to race with it. However - with IORING_SETUP_DEFER_TASKRUN - this is no longer the case and the work might be defered, giving userspace a chance to change data being referred to in the request. Instead _always_ prep_async for drain requests, which is simpler anyway and removes this issue. Cc: stable@vger.kernel.org Fixes: c0e0d6ba25f1 ("io_uring: add IORING_SETUP_DEFER_TASKRUN") Signed-off-by: Dylan Yudaken <dylany@meta.com> Link: https://lore.kernel.org/r/20230127105911.2420061-1-dylany@meta.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--io_uring/io_uring.c18
1 files changed, 8 insertions, 10 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 0a4efada9b3c..db623b3185c8 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1765,17 +1765,12 @@ queue:
}
spin_unlock(&ctx->completion_lock);
- ret = io_req_prep_async(req);
- if (ret) {
-fail:
- io_req_defer_failed(req, ret);
- return;
- }
io_prep_async_link(req);
de = kmalloc(sizeof(*de), GFP_KERNEL);
if (!de) {
ret = -ENOMEM;
- goto fail;
+ io_req_defer_failed(req, ret);
+ return;
}
spin_lock(&ctx->completion_lock);
@@ -2048,13 +2043,16 @@ static void io_queue_sqe_fallback(struct io_kiocb *req)
req->flags &= ~REQ_F_HARDLINK;
req->flags |= REQ_F_LINK;
io_req_defer_failed(req, req->cqe.res);
- } else if (unlikely(req->ctx->drain_active)) {
- io_drain_req(req);
} else {
int ret = io_req_prep_async(req);
- if (unlikely(ret))
+ if (unlikely(ret)) {
io_req_defer_failed(req, ret);
+ return;
+ }
+
+ if (unlikely(req->ctx->drain_active))
+ io_drain_req(req);
else
io_queue_iowq(req, NULL);
}