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authorMushahid Hussain <mushi.shar@gmail.com>2022-10-10 19:57:20 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-11-09 17:21:55 +0300
commit0fc801f8018000c8e64a275a20cb1da7c54e46df (patch)
tree9caa2472134e41b96c76b2e5e8136744c8fd4f12 /drivers/accessibility
parent38e9f21f648ed3f9125fe09378da9b2eb08b12d9 (diff)
downloadlinux-0fc801f8018000c8e64a275a20cb1da7c54e46df.tar.xz
speakup: fix a segfault caused by switching consoles
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: 2610df41489f ("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>
Diffstat (limited to 'drivers/accessibility')
-rw-r--r--drivers/accessibility/speakup/main.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/accessibility/speakup/main.c b/drivers/accessibility/speakup/main.c
index f52265293482..73db0cb44fc7 100644
--- a/drivers/accessibility/speakup/main.c
+++ b/drivers/accessibility/speakup/main.c
@@ -1778,7 +1778,7 @@ static void speakup_con_update(struct vc_data *vc)
{
unsigned long flags;
- if (!speakup_console[vc->vc_num] || spk_parked)
+ if (!speakup_console[vc->vc_num] || spk_parked || !synth)
return;
if (!spin_trylock_irqsave(&speakup_info.spinlock, flags))
/* Speakup output, discard */