From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
io-uring@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] io_uring: fix current->mm NULL dereference on exit
Date: Wed, 24 Jun 2020 19:50:08 +0300 [thread overview]
Message-ID: <c57f2702db6a13acc194b20a34bdef06eafcc00f.1593016907.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1593016907.git.asml.silence@gmail.com>
Don't reissue requests from io_iopoll_reap_events(), the task may not
have mm, which ends up with NULL. It's better to kill everything off on
exit anyway.
[ 677.734670] RIP: 0010:io_iopoll_complete+0x27e/0x630
...
[ 677.734679] Call Trace:
[ 677.734695] ? __send_signal+0x1f2/0x420
[ 677.734698] ? _raw_spin_unlock_irqrestore+0x24/0x40
[ 677.734699] ? send_signal+0xf5/0x140
[ 677.734700] io_iopoll_getevents+0x12f/0x1a0
[ 677.734702] io_iopoll_reap_events.part.0+0x5e/0xa0
[ 677.734703] io_ring_ctx_wait_and_kill+0x132/0x1c0
[ 677.734704] io_uring_release+0x20/0x30
[ 677.734706] __fput+0xcd/0x230
[ 677.734707] ____fput+0xe/0x10
[ 677.734709] task_work_run+0x67/0xa0
[ 677.734710] do_exit+0x35d/0xb70
[ 677.734712] do_group_exit+0x43/0xa0
[ 677.734713] get_signal+0x140/0x900
[ 677.734715] do_signal+0x37/0x780
[ 677.734717] ? enqueue_hrtimer+0x41/0xb0
[ 677.734718] ? recalibrate_cpu_khz+0x10/0x10
[ 677.734720] ? ktime_get+0x3e/0xa0
[ 677.734721] ? lapic_next_deadline+0x26/0x30
[ 677.734723] ? tick_program_event+0x4d/0x90
[ 677.734724] ? __hrtimer_get_next_event+0x4d/0x80
[ 677.734726] __prepare_exit_to_usermode+0x126/0x1c0
[ 677.734741] prepare_exit_to_usermode+0x9/0x40
[ 677.734742] idtentry_exit_cond_rcu+0x4c/0x60
[ 677.734743] sysvec_reschedule_ipi+0x92/0x160
[ 677.734744] ? asm_sysvec_reschedule_ipi+0xa/0x20
[ 677.734745] asm_sysvec_reschedule_ipi+0x12/0x20
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index fb88a537f471..578ec2e39712 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -884,6 +884,7 @@ enum io_mem_account {
ACCT_PINNED,
};
+static void io_complete_rw_common(struct kiocb *kiocb, long res);
static void io_wq_submit_work(struct io_wq_work **workptr);
static void io_cqring_fill_event(struct io_kiocb *req, long res);
static void io_put_req(struct io_kiocb *req);
@@ -1756,6 +1757,14 @@ static void io_iopoll_queue(struct list_head *again)
do {
req = list_first_entry(again, struct io_kiocb, list);
list_del(&req->list);
+
+ /* shouldn't happen unless io_uring is dying, cancel reqs */
+ if (unlikely(!current->mm)) {
+ io_complete_rw_common(&req->rw.kiocb, -EAGAIN);
+ io_put_req(req);
+ continue;
+ }
+
refcount_inc(&req->refs);
io_queue_async_work(req);
} while (!list_empty(again));
--
2.24.0
next prev parent reply other threads:[~2020-06-24 16:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-24 16:50 [PATCH 0/3] iopoll fixes Pavel Begunkov
2020-06-24 16:50 ` [PATCH 1/3] io_uring: fix hanging iopoll in case of -EAGAIN Pavel Begunkov
2020-06-24 16:50 ` Pavel Begunkov [this message]
2020-06-24 16:50 ` [PATCH 3/3] io_uring: fix NULL-mm for linked reqs Pavel Begunkov
2020-06-24 17:03 ` [PATCH 0/3] iopoll fixes Pavel Begunkov
2020-06-24 19:46 ` Jens Axboe
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