Aadded support for compilation on arm64 (aarch64) #5
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This commit allows you to compile the kernel on devices with arm64 (aarch64) processor architecture. For successful compilation on arm64 (aarch64) you need to specify the HOST_ARCH variable thus "export HOST_ARCH=$(arch)" in your bash script or terminal window
SahilSonar
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Apr 23, 2022
[ Upstream commit ef27324e2cb7bb24542d6cb2571740eefe6b00dc ]
Our detector found a concurrent use-after-free bug when detaching an
NCI device. The main reason for this bug is the unexpected scheduling
between the used delayed mechanism (timer and workqueue).
The race can be demonstrated below:
Thread-1 Thread-2
| nci_dev_up()
| nci_open_device()
| __nci_request(nci_reset_req)
| nci_send_cmd
| queue_work(cmd_work)
nci_unregister_device() |
nci_close_device() | ...
del_timer_sync(cmd_timer)[1] |
... | Worker
nci_free_device() | nci_cmd_work()
kfree(ndev)[3] | mod_timer(cmd_timer)[2]
In short, the cleanup routine thought that the cmd_timer has already
been detached by [1] but the mod_timer can re-attach the timer [2], even
it is already released [3], resulting in UAF.
This UAF is easy to trigger, crash trace by POC is like below
[ 66.703713] ==================================================================
[ 66.703974] BUG: KASAN: use-after-free in enqueue_timer+0x448/0x490
[ 66.703974] Write of size 8 at addr ffff888009fb7058 by task kworker/u4:1/33
[ 66.703974]
[ 66.703974] CPU: 1 PID: 33 Comm: kworker/u4:1 Not tainted 5.18.0-rc2 #5
[ 66.703974] Workqueue: nfc2_nci_cmd_wq nci_cmd_work
[ 66.703974] Call Trace:
[ 66.703974] <TASK>
[ 66.703974] dump_stack_lvl+0x57/0x7d
[ 66.703974] print_report.cold+0x5e/0x5db
[ 66.703974] ? enqueue_timer+0x448/0x490
[ 66.703974] kasan_report+0xbe/0x1c0
[ 66.703974] ? enqueue_timer+0x448/0x490
[ 66.703974] enqueue_timer+0x448/0x490
[ 66.703974] __mod_timer+0x5e6/0xb80
[ 66.703974] ? mark_held_locks+0x9e/0xe0
[ 66.703974] ? try_to_del_timer_sync+0xf0/0xf0
[ 66.703974] ? lockdep_hardirqs_on_prepare+0x17b/0x410
[ 66.703974] ? queue_work_on+0x61/0x80
[ 66.703974] ? lockdep_hardirqs_on+0xbf/0x130
[ 66.703974] process_one_work+0x8bb/0x1510
[ 66.703974] ? lockdep_hardirqs_on_prepare+0x410/0x410
[ 66.703974] ? pwq_dec_nr_in_flight+0x230/0x230
[ 66.703974] ? rwlock_bug.part.0+0x90/0x90
[ 66.703974] ? _raw_spin_lock_irq+0x41/0x50
[ 66.703974] worker_thread+0x575/0x1190
[ 66.703974] ? process_one_work+0x1510/0x1510
[ 66.703974] kthread+0x2a0/0x340
[ 66.703974] ? kthread_complete_and_exit+0x20/0x20
[ 66.703974] ret_from_fork+0x22/0x30
[ 66.703974] </TASK>
[ 66.703974]
[ 66.703974] Allocated by task 267:
[ 66.703974] kasan_save_stack+0x1e/0x40
[ 66.703974] __kasan_kmalloc+0x81/0xa0
[ 66.703974] nci_allocate_device+0xd3/0x390
[ 66.703974] nfcmrvl_nci_register_dev+0x183/0x2c0
[ 66.703974] nfcmrvl_nci_uart_open+0xf2/0x1dd
[ 66.703974] nci_uart_tty_ioctl+0x2c3/0x4a0
[ 66.703974] tty_ioctl+0x764/0x1310
[ 66.703974] __x64_sys_ioctl+0x122/0x190
[ 66.703974] do_syscall_64+0x3b/0x90
[ 66.703974] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 66.703974]
[ 66.703974] Freed by task 406:
[ 66.703974] kasan_save_stack+0x1e/0x40
[ 66.703974] kasan_set_track+0x21/0x30
[ 66.703974] kasan_set_free_info+0x20/0x30
[ 66.703974] __kasan_slab_free+0x108/0x170
[ 66.703974] kfree+0xb0/0x330
[ 66.703974] nfcmrvl_nci_unregister_dev+0x90/0xd0
[ 66.703974] nci_uart_tty_close+0xdf/0x180
[ 66.703974] tty_ldisc_kill+0x73/0x110
[ 66.703974] tty_ldisc_hangup+0x281/0x5b0
[ 66.703974] __tty_hangup.part.0+0x431/0x890
[ 66.703974] tty_release+0x3a8/0xc80
[ 66.703974] __fput+0x1f0/0x8c0
[ 66.703974] task_work_run+0xc9/0x170
[ 66.703974] exit_to_user_mode_prepare+0x194/0x1a0
[ 66.703974] syscall_exit_to_user_mode+0x19/0x50
[ 66.703974] do_syscall_64+0x48/0x90
[ 66.703974] entry_SYSCALL_64_after_hwframe+0x44/0xae
To fix the UAF, this patch adds flush_workqueue() to ensure the
nci_cmd_work is finished before the following del_timer_sync.
This combination will promise the timer is actually detached.
Fixes: 6a2968a ("NFC: basic NCI protocol implementation")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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This commit allows you to compile the kernel
on devices with arm64 (aarch64) processor architecture.
For successful compilation on arm64 (aarch64) you need to specify
the HOST_ARCH variable thus
"export HOST_ARCH=$(arch)"
in your bash script or terminal window