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authorJens Axboe <axboe@kernel.dk>2020-08-11 08:04:14 -0600
committerJens Axboe <axboe@kernel.dk>2020-08-11 08:09:13 -0600
commit6d816e088c359866f9867057e04f244c608c42fe (patch)
tree2b27bdab84603e31011b7aeb19b95b1a18e6934c /fs/io_uring.c
parentefa8480a831673bb52400df9dbe5da0aacda97bf (diff)
io_uring: hold 'ctx' reference around task_work queue + execute
We're holding the request reference, but we need to go one higher to ensure that the ctx remains valid after the request has finished. If the ring is closed with pending task_work inflight, and the given io_kiocb finishes sync during issue, then we need a reference to the ring itself around the task_work execution cycle. Cc: stable@vger.kernel.org # v5.7+ Reported-by: syzbot+9b260fc33297966f5a8e@syzkaller.appspotmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
-rw-r--r--fs/io_uring.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5488698189da..99582cf5106b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1821,8 +1821,10 @@ static void __io_req_task_submit(struct io_kiocb *req)
static void io_req_task_submit(struct callback_head *cb)
{
struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work);
+ struct io_ring_ctx *ctx = req->ctx;
__io_req_task_submit(req);
+ percpu_ref_put(&ctx->refs);
}
static void io_req_task_queue(struct io_kiocb *req)
@@ -1830,6 +1832,7 @@ static void io_req_task_queue(struct io_kiocb *req)
int ret;
init_task_work(&req->task_work, io_req_task_submit);
+ percpu_ref_get(&req->ctx->refs);
ret = io_req_task_work_add(req, &req->task_work);
if (unlikely(ret)) {
@@ -2318,6 +2321,8 @@ static void io_rw_resubmit(struct callback_head *cb)
refcount_inc(&req->refs);
io_queue_async_work(req);
}
+
+ percpu_ref_put(&ctx->refs);
}
#endif
@@ -2330,6 +2335,8 @@ static bool io_rw_reissue(struct io_kiocb *req, long res)
return false;
init_task_work(&req->task_work, io_rw_resubmit);
+ percpu_ref_get(&req->ctx->refs);
+
ret = io_req_task_work_add(req, &req->task_work);
if (!ret)
return true;
@@ -3033,6 +3040,8 @@ static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode,
list_del_init(&wait->entry);
init_task_work(&req->task_work, io_req_task_submit);
+ percpu_ref_get(&req->ctx->refs);
+
/* submit ref gets dropped, acquire a new one */
refcount_inc(&req->refs);
ret = io_req_task_work_add(req, &req->task_work);
@@ -4565,6 +4574,8 @@ static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll,
req->result = mask;
init_task_work(&req->task_work, func);
+ percpu_ref_get(&req->ctx->refs);
+
/*
* If this fails, then the task is exiting. When a task exits, the
* work gets canceled, so just cancel this request as well instead
@@ -4652,11 +4663,13 @@ static void io_poll_task_handler(struct io_kiocb *req, struct io_kiocb **nxt)
static void io_poll_task_func(struct callback_head *cb)
{
struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work);
+ struct io_ring_ctx *ctx = req->ctx;
struct io_kiocb *nxt = NULL;
io_poll_task_handler(req, &nxt);
if (nxt)
__io_req_task_submit(nxt);
+ percpu_ref_put(&ctx->refs);
}
static int io_poll_double_wake(struct wait_queue_entry *wait, unsigned mode,
@@ -4752,6 +4765,7 @@ static void io_async_task_func(struct callback_head *cb)
if (io_poll_rewait(req, &apoll->poll)) {
spin_unlock_irq(&ctx->completion_lock);
+ percpu_ref_put(&ctx->refs);
return;
}
@@ -4767,6 +4781,7 @@ static void io_async_task_func(struct callback_head *cb)
else
__io_req_task_cancel(req, -ECANCELED);
+ percpu_ref_put(&ctx->refs);
kfree(apoll->double_poll);
kfree(apoll);
}