[PATCH 6.1.y 5.15.y 5.10.y 5.4.y 4.19.y] vt: prevent kernel-infoleak in con_font_get()

[Jeongjun Park <aha310510@gmail.com>]

commit f956052e00de211b5c9ebaa1958366c23f82ee9e upstream.

font.data may not initialize all memory spaces depending on the implementation
of vc->vc_sw->con_font_get. This may cause info-leak, so to prevent this, it
is safest to modify it to initialize the allocated memory space to 0, and it
generally does not affect the overall performance of the system.

Cc: stable@vger.kernel.org
Reported-by: syzbot+955da2d57931604ee691@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Link: https://lore.kernel.org/r/20241010174619.59662-1-aha310510@gmail.com
---
 drivers/tty/vt/vt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 5f1183b0b89d..800979e8d5b6 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -4398,7 +4398,7 @@ static int con_font_get(struct vc_data *vc, struct console_font_op *op)
 	int c;
 
 	if (op->data) {
-		font.data = kmalloc(max_font_size, GFP_KERNEL);
+		font.data = kzalloc(max_font_size, GFP_KERNEL);
 		if (!font.data)
 			return -ENOMEM;
 	} else
--