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cd13f1d002
commit dad1b1242f upstream.
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.
Cc: <stable@vger.kernel.org> # 5.5+
Reported-by: Abaci Fuzz <abaci@linux.alibaba.com>
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.