commit 0fc801f8018000c8e64a275a20cb1da7c54e46df upstream.
This patch fixes a segfault by adding a null check on synth in
speakup_con_update(). The segfault can be reproduced as follows:
- Login into a text console
- Load speakup and speakup_soft modules
- Remove speakup_soft
- Switch to a graphics console
This is caused by lack of a null check on `synth` in
speakup_con_update().
Here's the sequence that causes the segfault:
- When we remove the speakup_soft, synth_release() sets the synth
to null.
- After that, when we change the virtual console to graphics
console, vt_notifier_call() is fired, which then calls
speakup_con_update().
- Inside speakup_con_update() there's no null check on synth,
so it calls synth_printf().
- Inside synth_printf(), synth_buffer_add() and synth_start(),
both access synth, when it is null and causing a segfault.
Therefore adding a null check on synth solves the issue.
Fixes: 2610df4148 ("staging: speakup: Add pause command used on switching to graphical mode")
Cc: stable <stable@kernel.org>
Signed-off-by: Mushahid Hussain <mushi.shar@gmail.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://lore.kernel.org/r/20221010165720.397042-1-mushi.shar@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull tty/serial updates from Greg KH:
"Here is the large set of TTY and Serial driver patches for 5.9-rc1.
Lots of bugfixes in here, thanks to syzbot fuzzing for serial and vt
and console code.
Other highlights include:
- much needed vt/vc code cleanup from Jiri Slaby
- 8250 driver fixes and additions
- various serial driver updates and feature enhancements
- locking cleanup for serial/console initializations
- other minor cleanups
All of these have been in linux-next with no reported issues"
* tag 'tty-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (90 commits)
MAINTAINERS: enlist Greg formally for console stuff
vgacon: Fix for missing check in scrollback handling
Revert "serial: 8250: Let serial core initialise spin lock"
serial: 8250: Let serial core initialise spin lock
tty: keyboard, do not speculate on func_table index
serial: stm32: Add RS485 RTS GPIO control
serial: 8250_dw: Fix common clocks usage race condition
serial: 8250_dw: Pass the same rate to the clk round and set rate methods
serial: 8250_dw: Simplify the ref clock rate setting procedure
serial: 8250: Add 8250 port clock update method
tty: serial: imx: add imx earlycon driver
tty: serial: imx: enable imx serial console port as module
tty/synclink: remove leftover bits of non-PCI card support
tty: Use the preferred form for passing the size of a structure type
tty: Fix identation issues in struct serial_struct32
tty: Avoid the use of one-element arrays
serial: msm_serial: add sparse context annotation
serial: pmac_zilog: add sparse context annotation
newport_con: vc_color is now in state
serial: imx: use hrtimers for rs485 delays
...
