vt: prevent kernel-infoleak in con_font_get()

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: 05e2600cb0a4 ("VT: Bump font size limitation to 64x128 pixels")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Link: https://lore.kernel.org/r/20241010174619.59662-1-aha310510@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index a070f2e7d960f7f29158b74a3649f414b3935f99..5d9de3a53548b18e07e11881d37c7bb5c623ae6d 100644 (file)
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -4603,7 +4603,7 @@ 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