From patchwork Sat May 27 09:19:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Helge Deller X-Patchwork-Id: 13257602 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08147C7EE2F for ; Sat, 27 May 2023 09:19:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231922AbjE0JTK (ORCPT ); Sat, 27 May 2023 05:19:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229717AbjE0JTK (ORCPT ); Sat, 27 May 2023 05:19:10 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C795EE3 for ; Sat, 27 May 2023 02:19:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.de; s=s31663417; t=1685179143; i=deller@gmx.de; bh=Xk8e0o79rU5qYQZ41Nvm9kC6xi+2UGglRFIowace/L4=; h=X-UI-Sender-Class:Date:From:To:Subject; b=eb/6Mrz8yN0LZrWkBdEQ80ElnlY7V0v3Jz7nAkMow5DkAgYEkfBXeBCPhOSVGhS4I wcSjlkijoNUVkCHZ9xf1hLvRa6W5x+V1jN1uRo7APnqywWm4BtD3AkD3oi2ZZP+Z/j /Y2w2YsDRXN6/ymEEu+x8EzxWoD3IsPDdyXKi5xWjtXnT32whE/kMO5Z5R0APRaWy3 m93vPf7AwgJfDvH5I+jPq18HBZ8d77IzHCxjrUMdkru79Ok7r4vrnpOWsKLKkMc8ke hfcmSOzbZnaxgYxG3p5wNtAEicfIAYs4kTiWhuAkSuyecWs0NvSUwxxQANU9Aey0cJ EIqeKcG7efz1A== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from ls3530 ([94.134.159.182]) by mail.gmx.net (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1N0G1d-1qHE482EB5-00xHIq; Sat, 27 May 2023 11:19:03 +0200 Date: Sat, 27 May 2023 11:19:02 +0200 From: Helge Deller To: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH] fbcon: Avoid showing softcursor if font not available Message-ID: MIME-Version: 1.0 Content-Disposition: inline X-Provags-ID: V03:K1:Hy1M/kWlW75ynhsKITDLJX25gY+535q2YlSnrIgMgWXEZZ7WGcF c4OZxQkf16ySpObXzo1ssgyAO/+xiRSk5ieCTAzduAZPP3PuR+OWuM1Hq8uIct0EF9SfODj NVtI4AP6yVqBIfFhOH9yDQMl3K349YhKl1b4N6ZrBuau2fSvrxVSmZ3ZWYuMubc8PRHre1N NmrwdRQqq2KcpbQ2AixTg== UI-OutboundReport: notjunk:1;M01:P0:WSUFyarqV14=;LjvD7toyDOCzg5nhm73lXV+k5D/ 6rZE5ixcjOpNn+V1sgTIdUUheydzn+C6NSDP3zGDisCD2bkdqRGGTNnXM1CuS1ZmXMXFLqCKj fqa09ZWigxq1M7iz/clUx5dq19sLSf2Cdg6WVI165x6GEo8dbOF/7jeAJmUh41uhSLUXgL7PF j24qegluTo5UR2PhE7eN7cAQ2HRdfbtldkr5NzKHxd6GaF/+6gPZn4s426GAfgE6clVsQ/Hxs UaIkTvqULS+ktgXd9Jqu8bw/HuDhSzMRKrjafdg6t5NVVeSWt/uOhQ4hVY4dHzXDfxKiXeONj uplKp3qbwJ26J5EiZ9F2RkrVVhZfPMKW0fQrLHyCeiDrbuZpEc6hkW8IuOtJrg5dzwFxtumX+ iS7spwv2u8qpqsrY1VFfdRkwUNjDL3TwVlr9xGdhI1UFfXF5j/wdyFlj78cfZ/1QelhSlXJ94 VFxG0eOX5LMfZYLtQHLAMcfjWSHZhU9Pg5rWDw435Klap41iEztzt1/U7TJqGP/LBY/YsW2+d jmoL58KJnsyMh2EN0ddFqEQdQtj74Y183xYbzSDmbJrL7d6XUIUxL10w+H4fshocrO6CGQrfV fogK9LWYaMaW2hhe9ZIgIop9t6HdvGQ/E8cKqCOGVuIr2XKPIzLzRT03mWGX7e99P2muKujLO KqGMSgA2/EthfN1b5/HZ5Fc6iGdWzDQsDyqpHFHD/xNSXrWMZbshou/dkqIqxhscBHKJHNRzP +V7DzuSPu1V1kuvsAeLr3o4VO5yNzUKghF1enJwitZIH2g8NiB7KQkhEg/WgCoZGlpr0AlHhG KqNOHBhaM2TrI/3g0UuJYJabHgvlS0dGbATRLyUw7CNZJwXelNT8gFkuEt+YNCxr3cAL905vK nO2YXzy/ZAl4gx4PenlrthYc5uRf6Sa5LWO562r8oXkTL+2CIBjEFoynYPuCVXR5jnDKNmYaX soFpxKzpxF7+13bk9oBSQhvxiZg= Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org syzbot repored this bug in the softcursor code: BUG: KASAN: null-ptr-deref in soft_cursor+0x384/0x6b4 drivers/video/fbdev/core/softcursor.c:70 Read of size 16 at addr 0000000000000200 by task kworker/u4:1/12 CPU: 0 PID: 12 Comm: kworker/u4:1 Not tainted 6.4.0-rc3-syzkaller-geb0f1697d729 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 Workqueue: events_power_efficient fb_flashcursor Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233 show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106 print_report+0xe4/0x514 mm/kasan/report.c:465 kasan_report+0xd4/0x130 mm/kasan/report.c:572 kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:187 __asan_memcpy+0x3c/0x84 mm/kasan/shadow.c:105 soft_cursor+0x384/0x6b4 drivers/video/fbdev/core/softcursor.c:70 bit_cursor+0x113c/0x1a64 drivers/video/fbdev/core/bitblit.c:377 fb_flashcursor+0x35c/0x54c drivers/video/fbdev/core/fbcon.c:380 process_one_work+0x788/0x12d4 kernel/workqueue.c:2405 worker_thread+0x8e0/0xfe8 kernel/workqueue.c:2552 kthread+0x288/0x310 kernel/kthread.c:379 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:853 This fix let bit_cursor() bail out early when a font bitmap isn't available yet. Signed-off-by: Helge Deller Cc: stable@kernel.org Reported-by: syzbot+d910bd780e6efac35869@syzkaller.appspotmail.com Acked-by: Sam Ravnborg --- drivers/video/fbdev/core/bitblit.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.40.1 diff --git a/drivers/video/fbdev/core/bitblit.c b/drivers/video/fbdev/core/bitblit.c index f98e8f298bc1..8587c9da0670 100644 --- a/drivers/video/fbdev/core/bitblit.c +++ b/drivers/video/fbdev/core/bitblit.c @@ -247,6 +247,9 @@ static void bit_cursor(struct vc_data *vc, struct fb_info *info, int mode, cursor.set = 0; + if (!vc->vc_font.data) + return; + c = scr_readw((u16 *) vc->vc_pos); attribute = get_attribute(info, c); src = vc->vc_font.data + ((c & charmask) * (w * vc->vc_font.height));