Fixes for 5.10

[thirdparty/kernel/stable-queue.git] / queue-5.10 / speakup-fix-8bit-characters-from-direct-synth.patch

From 58e334400f719036a246cbc04ad462bb5f9dbea0 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Sun, 4 Feb 2024 16:57:36 +0100
Subject: speakup: Fix 8bit characters from direct synth

From: Samuel Thibault <samuel.thibault@ens-lyon.org>

[ Upstream commit b6c8dafc9d86eb77e502bb018ec4105e8d2fbf78 ]

When userland echoes 8bit characters to /dev/synth with e.g.

echo -e '\xe9' > /dev/synth

synth_write would get characters beyond 0x7f, and thus negative when
char is signed.  When given to synth_buffer_add which takes a u16, this
would sign-extend and produce a U+ffxy character rather than U+xy.
Users thus get garbled text instead of accents in their output.

Let's fix this by making sure that we read unsigned characters.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Fixes: 89fc2ae80bb1 ("speakup: extend synth buffer to 16bit unicode characters")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240204155736.2oh4ot7tiaa2wpbh@begin
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/accessibility/speakup/synth.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/accessibility/speakup/synth.c b/drivers/accessibility/speakup/synth.c
index ac47dbac72075..82cfc5ec6bdf9 100644
--- a/drivers/accessibility/speakup/synth.c
+++ b/drivers/accessibility/speakup/synth.c
@@ -208,8 +208,10 @@ void spk_do_flush(void)
 	wake_up_process(speakup_task);
 }
 
-void synth_write(const char *buf, size_t count)
+void synth_write(const char *_buf, size_t count)
 {
+	const unsigned char *buf = (const unsigned char *) _buf;
+
 	while (count--)
 		synth_buffer_add(*buf++);
 	synth_start();
-- 
2.43.0