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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Daniel Vetter <daniel@ffwll.ch>, Helge Deller <deller@gmx.de>,
	Shigeru Yoshida <syoshida@redhat.com>
Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: [PATCH] fbdev: fbcon: release buffer when fbcon_do_set_font() failed
Date: Tue, 6 Dec 2022 07:10:31 +0900	[thread overview]
Message-ID: <d37c0147-3605-a876-9b85-16bcbc05eaa6@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <000000000000e2efc305ef0d341f@google.com>

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@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+25bdb7b1703639abd498@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


  reply	other threads:[~2022-12-05 22:12 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-05  4:34 [syzbot] memory leak in fbcon_set_font (2) syzbot
2022-12-05 22:10 ` Tetsuo Handa [this message]
2022-12-10 16:18   ` [PATCH] fbdev: fbcon: release buffer when fbcon_do_set_font() failed Helge Deller

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