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2b04495e21
Hulk Robot reports incorrect sp->rx_count_cooked value in decode_std_command().
This should be caused by the subtracting from sp->rx_count_cooked before.
It seems that sp->rx_count_cooked value is changed to 0, which bypassed the
previous judgment.
The situation is shown below:
(Thread 1) | (Thread 2)
decode_std_command() | resync_tnc()
... |
if (rest == 2) |
sp->rx_count_cooked -= 2; |
else if (rest == 3) | ...
| sp->rx_count_cooked = 0;
sp->rx_count_cooked -= 1; |
for (i = 0; i < sp->rx_count_cooked; i++) // report error
checksum += sp->cooked_buf[i];
sp->rx_count_cooked is a shared variable but is not protected by a lock.
The same applies to sp->rx_count. This patch adds a lock to fix the bug.
The fail log is shown below:
=======================================================================
UBSAN: array-index-out-of-bounds in drivers/net/hamradio/6pack.c:925:31
index 400 is out of range for type 'unsigned char [400]'
CPU: 3 PID: 7433 Comm: kworker/u10:1 Not tainted 5.18.0-rc5-00163-g4b97bac0756a #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Workqueue: events_unbound flush_to_ldisc
Call Trace:
<TASK>
dump_stack_lvl+0xcd/0x134
ubsan_epilogue+0xb/0x50
__ubsan_handle_out_of_bounds.cold+0x62/0x6c
sixpack_receive_buf+0xfda/0x1330
tty_ldisc_receive_buf+0x13e/0x180
tty_port_default_receive_buf+0x6d/0xa0
flush_to_ldisc+0x213/0x3f0
process_one_work+0x98f/0x1620
worker_thread+0x665/0x1080
kthread+0x2e9/0x3a0
ret_from_fork+0x1f/0x30
...
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Xu Jia <xujia39@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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.