[PATCH] fbdev: fbcon: release buffer when fbcon_do_set_font() failed

[Tetsuo Handa]

syzbot is reporting memory leak at fbcon_do_set_font() [1], for
commit a5a923038d70 ("fbdev: fbcon: Properly revert changes when
vc_resize() failed") missed that the buffer might be newly allocated
by fbcon_set_font().

Link: https://syzkaller.appspot.com/bug?extid=25bdb7b1703639abd498 [1]
Reported-by: syzbot <syzbot+25bdb7b1703639abd498 at syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+25bdb7b1703639abd498 at syzkaller.appspotmail.com>
Fixes: a5a923038d70 ("fbdev: fbcon: Properly revert changes when vc_resize() failed")
---
 drivers/video/fbdev/core/fbcon.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 098b62f7b701..8363f3b2b452 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -2450,7 +2450,8 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount,
 
 	if (userfont) {
 		p->userfont = old_userfont;
-		REFCOUNT(data)--;
+		if (--REFCOUNT(data) == 0)
+			kfree(data - FONT_EXTRA_WORDS * sizeof(int));
 	}
 
 	vc->vc_font.width = old_width;
-- 
2.34.1