From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5FA7220C477; Fri, 4 Oct 2024 18:26:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728066409; cv=none; b=m9HDH7PXiexekHqDL5SdtMZHwH91BDxJJ5SQkm84S3sB7RtQ+LMkxfYhorn5/mXpsdeQnkvU+F/jw9z0lQvBrYLfmZnU1S/bbc4HVGr6snSo0WX4gnN4Cv6Jcl6J3ErtQp8yZEavMbFqsYVwuVCR+8YdpqHFhQdlemC217ihUYU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728066409; c=relaxed/simple; bh=2YxxB5xVkoD6jz96nY3YkZRwTLB9OAWY2sZKh5LB/kc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FGDI0mrqv1EQDDPscKFpZaabNEmAxbE43sVGaI3iIqqWwKcbmds/pgfm2xLDMIzspvpyq0dAjpafqem5W7cPDRgyDFx4i1fitwQPxP5tcq+ZsAqCeQcTc+5H2vW/3sIF0IkNijHXYl6CcrzTYYovpTBOrzLjAL6hUWpS6nJRFS0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DQ+soxjb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DQ+soxjb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 736C0C4CECC; Fri, 4 Oct 2024 18:26:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728066408; bh=2YxxB5xVkoD6jz96nY3YkZRwTLB9OAWY2sZKh5LB/kc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DQ+soxjbjOn370g9i88IAwM7BkLFaJacLdqLW4QDdRXQBFys184pqIqkNTS9TqtME w5M3z620yEsykcjXX18/MnLKKjGGfknbHd2XlLvZWBWftGgNTYRRyxmTkEfXhGVii2 yHORqCKdBbtD8PRaFJm3HlKfBMh/ElqgvlpeCq/YY0fiaiJv69o1PgmVvtfSaGlZf3 qaw/pJtg5hIu/8yk/bEP+sa0WyyYKuN++o48xmKSxJDYFNy2u9aTRwK32pJkMniGo6 +7ZupRO7y2E4iM/dhQ5lY1NCwRYdHThXiVkzwXHrWYwi/KBr8XBcDzLrfJu9yBz6pl RNbPMJGxtnBPQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Qianqiang Liu , syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com, Helge Deller , Sasha Levin , daniel@ffwll.ch, jirislaby@kernel.org, gregkh@linuxfoundation.org, geert+renesas@glider.be, samuel.thibault@ens-lyon.org, tzimmermann@suse.de, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 6.6 56/58] fbcon: Fix a NULL pointer dereference issue in fbcon_putcs Date: Fri, 4 Oct 2024 14:24:29 -0400 Message-ID: <20241004182503.3672477-56-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241004182503.3672477-1-sashal@kernel.org> References: <20241004182503.3672477-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.54 Content-Transfer-Encoding: 8bit From: Qianqiang Liu [ Upstream commit 5b97eebcce1b4f3f07a71f635d6aa3af96c236e7 ] syzbot has found a NULL pointer dereference bug in fbcon. Here is the simplified C reproducer: struct param { uint8_t type; struct tiocl_selection ts; }; int main() { struct fb_con2fbmap con2fb; struct param param; int fd = open("/dev/fb1", 0, 0); con2fb.console = 0x19; con2fb.framebuffer = 0; ioctl(fd, FBIOPUT_CON2FBMAP, &con2fb); param.type = 2; param.ts.xs = 0; param.ts.ys = 0; param.ts.xe = 0; param.ts.ye = 0; param.ts.sel_mode = 0; int fd1 = open("/dev/tty1", O_RDWR, 0); ioctl(fd1, TIOCLINUX, ¶m); con2fb.console = 1; con2fb.framebuffer = 0; ioctl(fd, FBIOPUT_CON2FBMAP, &con2fb); return 0; } After calling ioctl(fd1, TIOCLINUX, ¶m), the subsequent ioctl(fd, FBIOPUT_CON2FBMAP, &con2fb) causes the kernel to follow a different execution path: set_con2fb_map -> con2fb_init_display -> fbcon_set_disp -> redraw_screen -> hide_cursor -> clear_selection -> highlight -> invert_screen -> do_update_region -> fbcon_putcs -> ops->putcs Since ops->putcs is a NULL pointer, this leads to a kernel panic. To prevent this, we need to call set_blitting_type() within set_con2fb_map() to properly initialize ops->putcs. Reported-by: syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3d613ae53c031502687a Tested-by: syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com Signed-off-by: Qianqiang Liu Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- drivers/video/fbdev/core/fbcon.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 24035b4f2cd70..405d587450ef8 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -847,6 +847,8 @@ static int set_con2fb_map(int unit, int newidx, int user) return err; fbcon_add_cursor_work(info); + } else if (vc) { + set_blitting_type(vc, info); } con2fb_map[unit] = newidx; -- 2.43.0