From c428d528f8a0aa70473cc9a87374ed4ec75626ec Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 4 Oct 2018 11:06:13 -0700
Subject: tty: wipe buffer.

commit c9a8e5fce009e3c601a43c49ea9dbcb25d1ffac5 upstream.

After we are done with the tty buffer, zero it out.

Reported-by: aszlig <aszlig@nix.build>
Tested-by: Milan Broz <gmazyland@gmail.com>
Tested-by: Daniel Zatovic <daniel.zatovic@gmail.com>
Tested-by: aszlig <aszlig@nix.build>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/tty_buffer.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 143deb62467d..0d3fc2dae23a 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -415,6 +415,8 @@ receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count)
 			disc->ops->receive_buf(tty, p, f, count);
 	}
 	head->read += count;
+	if (count > 0)
+		memset(p, 0, count);
 	return count;
 }
 
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