Mushahid Hussain a190a83db2 speakup: fix a segfault caused by switching consoles ... commit 0fc801f801 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>		2022-11-26 09:24:44 +01:00
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braille	Char / Misc driver updates for 5.14-rc1	2021-07-05 13:42:16 -07:00
speakup	speakup: fix a segfault caused by switching consoles	2022-11-26 09:24:44 +01:00
Kconfig	staging/speakup: Move out of staging	2020-07-29 14:02:41 +02:00
Makefile	staging/speakup: Move out of staging	2020-07-29 14:02:41 +02:00