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authorPavel Begunkov <asml.silence@gmail.com>2021-11-26 14:38:14 +0000
committerJens Axboe <axboe@kernel.dk>2021-11-26 08:35:43 -0700
commit617a89484debcd4e7999796d693cf0b77d2519de (patch)
tree6b6d008804b3b2fcfb3e932954311d8179e30247
parent674ee8e1b4a41d2fdffc885c55350c3fbb38c22a (diff)
io_uring: fail cancellation for EXITING tasks
WARNING: CPU: 1 PID: 20 at fs/io_uring.c:6269 io_try_cancel_userdata+0x3c5/0x640 fs/io_uring.c:6269 CPU: 1 PID: 20 Comm: kworker/1:0 Not tainted 5.16.0-rc1-syzkaller #0 Workqueue: events io_fallback_req_func RIP: 0010:io_try_cancel_userdata+0x3c5/0x640 fs/io_uring.c:6269 Call Trace: <TASK> io_req_task_link_timeout+0x6b/0x1e0 fs/io_uring.c:6886 io_fallback_req_func+0xf9/0x1ae fs/io_uring.c:1334 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298 worker_thread+0x658/0x11f0 kernel/workqueue.c:2445 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK> We need original task's context to do cancellations, so if it's dying and the callback is executed in a fallback mode, fail the cancellation attempt. Fixes: 89b263f6d56e6 ("io_uring: run linked timeouts from task_work") Cc: stable@kernel.org # 5.15+ Reported-by: syzbot+ab0cfe96c2b3cd1c1153@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/4c41c5f379c6941ad5a07cd48cb66ed62199cf7e.1637937097.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index a4c508a1e0cf..7dd112d44adf 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6882,10 +6882,11 @@ static inline struct file *io_file_get(struct io_ring_ctx *ctx,
static void io_req_task_link_timeout(struct io_kiocb *req, bool *locked)
{
struct io_kiocb *prev = req->timeout.prev;
- int ret;
+ int ret = -ENOENT;
if (prev) {
- ret = io_try_cancel_userdata(req, prev->user_data);
+ if (!(req->task->flags & PF_EXITING))
+ ret = io_try_cancel_userdata(req, prev->user_data);
io_req_complete_post(req, ret ?: -ETIME, 0);
io_put_req(prev);
} else {