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3560603ef8
commit d412275444 upstream.
Speakup has only one speakup_tty variable to store the tty it is managing. This
makes sense since its codebase currently assumes that there is only one user who
controls the screen reading.
That however means that we have to forbid using the line discipline several
times, otherwise the second closure would try to free a NULL ldisc_data, leading to
general protection fault: 0000 [#1] SMP KASAN PTI
RIP: 0010:spk_ttyio_ldisc_close+0x2c/0x60
Call Trace:
tty_ldisc_release+0xa2/0x340
tty_release_struct+0x17/0xd0
tty_release+0x9d9/0xcc0
__fput+0x231/0x740
task_work_run+0x12c/0x1a0
do_exit+0x9b5/0x2230
? release_task+0x1240/0x1240
? __do_page_fault+0x562/0xa30
do_group_exit+0xd5/0x2a0
__x64_sys_exit_group+0x35/0x40
do_syscall_64+0x89/0x2b0
? page_fault+0x8/0x30
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Cc: stable@vger.kernel.org
Reported-by: 秦世松 <qinshisong1205@gmail.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Tested-by: Shisong Qin <qinshisong1205@gmail.com>
Link: https://lore.kernel.org/r/20201110183541.fzgnlwhjpgqzjeth@function
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.