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| author | Mushahid Hussain <mushi.shar@gmail.com> | 2022-10-10 21:57:20 +0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-09 15:21:55 +0100 |
| commit | 0fc801f8018000c8e64a275a20cb1da7c54e46df (patch) | |
| tree | 9caa2472134e41b96c76b2e5e8136744c8fd4f12 /drivers/accessibility | |
| parent | 38e9f21f648ed3f9125fe09378da9b2eb08b12d9 (diff) | |
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.c | 2 |
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 */ |