From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>
Cc: [email protected], io-uring <[email protected]>
Subject: Re: [PATCH 5.10 1/5] io_uring: always let io_iopoll_complete() complete polled io.
Date: Mon, 7 Dec 2020 09:28:20 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <cf556b9b870c640690a1705c073fe955c01dab47.1607293068.git.asml.silence@gmail.com>
On Sun, Dec 6, 2020 at 3:26 PM Pavel Begunkov <[email protected]> wrote:
>
> From: Xiaoguang Wang <[email protected]>
>
> Abaci Fuzz reported a double-free or invalid-free BUG in io_commit_cqring():
> [ 95.504842] BUG: KASAN: double-free or invalid-free in io_commit_cqring+0x3ec/0x8e0
> [ 95.505921]
> [ 95.506225] CPU: 0 PID: 4037 Comm: io_wqe_worker-0 Tainted: G B
> W 5.10.0-rc5+ #1
> [ 95.507434] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
> [ 95.508248] Call Trace:
> [ 95.508683] dump_stack+0x107/0x163
> [ 95.509323] ? io_commit_cqring+0x3ec/0x8e0
> [ 95.509982] print_address_description.constprop.0+0x3e/0x60
> [ 95.510814] ? vprintk_func+0x98/0x140
> [ 95.511399] ? io_commit_cqring+0x3ec/0x8e0
> [ 95.512036] ? io_commit_cqring+0x3ec/0x8e0
> [ 95.512733] kasan_report_invalid_free+0x51/0x80
> [ 95.513431] ? io_commit_cqring+0x3ec/0x8e0
> [ 95.514047] __kasan_slab_free+0x141/0x160
> [ 95.514699] kfree+0xd1/0x390
> [ 95.515182] io_commit_cqring+0x3ec/0x8e0
> [ 95.515799] __io_req_complete.part.0+0x64/0x90
> [ 95.516483] io_wq_submit_work+0x1fa/0x260
> [ 95.517117] io_worker_handle_work+0xeac/0x1c00
> [ 95.517828] io_wqe_worker+0xc94/0x11a0
> [ 95.518438] ? io_worker_handle_work+0x1c00/0x1c00
> [ 95.519151] ? __kthread_parkme+0x11d/0x1d0
> [ 95.519806] ? io_worker_handle_work+0x1c00/0x1c00
> [ 95.520512] ? io_worker_handle_work+0x1c00/0x1c00
> [ 95.521211] kthread+0x396/0x470
> [ 95.521727] ? _raw_spin_unlock_irq+0x24/0x30
> [ 95.522380] ? kthread_mod_delayed_work+0x180/0x180
> [ 95.523108] ret_from_fork+0x22/0x30
> [ 95.523684]
> [ 95.523985] Allocated by task 4035:
> [ 95.524543] kasan_save_stack+0x1b/0x40
> [ 95.525136] __kasan_kmalloc.constprop.0+0xc2/0xd0
> [ 95.525882] kmem_cache_alloc_trace+0x17b/0x310
> [ 95.533930] io_queue_sqe+0x225/0xcb0
> [ 95.534505] io_submit_sqes+0x1768/0x25f0
> [ 95.535164] __x64_sys_io_uring_enter+0x89e/0xd10
> [ 95.535900] do_syscall_64+0x33/0x40
> [ 95.536465] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 95.537199]
> [ 95.537505] Freed by task 4035:
> [ 95.538003] kasan_save_stack+0x1b/0x40
> [ 95.538599] kasan_set_track+0x1c/0x30
> [ 95.539177] kasan_set_free_info+0x1b/0x30
> [ 95.539798] __kasan_slab_free+0x112/0x160
> [ 95.540427] kfree+0xd1/0x390
> [ 95.540910] io_commit_cqring+0x3ec/0x8e0
> [ 95.541516] io_iopoll_complete+0x914/0x1390
> [ 95.542150] io_do_iopoll+0x580/0x700
> [ 95.542724] io_iopoll_try_reap_events.part.0+0x108/0x200
> [ 95.543512] io_ring_ctx_wait_and_kill+0x118/0x340
> [ 95.544206] io_uring_release+0x43/0x50
> [ 95.544791] __fput+0x28d/0x940
> [ 95.545291] task_work_run+0xea/0x1b0
> [ 95.545873] do_exit+0xb6a/0x2c60
> [ 95.546400] do_group_exit+0x12a/0x320
> [ 95.546967] __x64_sys_exit_group+0x3f/0x50
> [ 95.547605] do_syscall_64+0x33/0x40
> [ 95.548155] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> The reason is that once we got a non EAGAIN error in io_wq_submit_work(),
> we'll complete req by calling io_req_complete(), which will hold completion_lock
> to call io_commit_cqring(), but for polled io, io_iopoll_complete() won't
> hold completion_lock to call io_commit_cqring(), then there maybe concurrent
> access to ctx->defer_list, double free may happen.
>
> To fix this bug, we always let io_iopoll_complete() complete polled io.
This patch is causing hangs with iopoll testing, if you end up getting
-EAGAIN on request submission. I've dropped it.
Reproducible with test/iopoll /dev/somedevice
where somedevice has a low queue depth and hits request starvation
during the test.
--
Jens Axboe
next prev parent reply other threads:[~2020-12-07 16:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-06 22:22 [PATCH 5.10 0/5] iopoll fixes Pavel Begunkov
2020-12-06 22:22 ` [PATCH 5.10 1/5] io_uring: always let io_iopoll_complete() complete polled io Pavel Begunkov
2020-12-07 16:28 ` Jens Axboe [this message]
2020-12-08 19:12 ` Pavel Begunkov
2020-12-08 19:17 ` Jens Axboe
2020-12-08 19:24 ` Pavel Begunkov
2020-12-08 21:10 ` Jens Axboe
2020-12-09 20:17 ` Pavel Begunkov
2020-12-10 17:38 ` Pavel Begunkov
2020-12-06 22:22 ` [PATCH 5.10 2/5] io_uring: fix racy IOPOLL completions Pavel Begunkov
2020-12-07 18:31 ` Pavel Begunkov
2020-12-06 22:22 ` [PATCH 5.10 3/5] io_uring: fix racy IOPOLL flush overflow Pavel Begunkov
2020-12-06 22:22 ` [PATCH 5.10 4/5] io_uring: fix io_cqring_events()'s noflush Pavel Begunkov
2020-12-06 22:22 ` [PATCH 5.10 5/5] io_uring: fix mis-seting personality's creds Pavel Begunkov
2020-12-07 15:05 ` [PATCH 5.10 0/5] iopoll fixes Jens Axboe
2020-12-07 15:24 ` Pavel Begunkov
2020-12-07 15:28 ` Jens Axboe
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