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 3AF9B1A0724; Mon, 14 Oct 2024 14:27:59 +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=1728916079; cv=none; b=vAiqYP3UMpTFwuVrdIOU+E8xIA6v6L4PlmaKFPZ6EON0ebneZVFt0InnHmcaoFAcGn2vt+trT+69HVlAJGJ5hNlqGOj6NDzySkPQkMecvoxUyq3eJPqOKi8JZBXK3Dm8/k0wi44Ii2fsyvdo+G/sCvqncv7QHefMI7lruUlvYuI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728916079; c=relaxed/simple; bh=Zi5ecuMFyaitR+E3FAFL/d0Msx/8VwAXriNN7u+NInA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=StITY+pfb/0LyH5OJeSpJbDuUlaRzC/MjeKBrERS2VkFerGCd2uxZQAk1rTgBpsAbbsXz6hvFmwHzHd249KrDAqMEsSTTjr5e23aFM4dfthgwwUkVlzKBNA2qvSPZEjpvtqwEc5BsEAxc5ivDnYQasTTujme6N9gAnnc9iUZJkU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=O6MJSTtP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="O6MJSTtP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7707C4CEC3; Mon, 14 Oct 2024 14:27:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728916079; bh=Zi5ecuMFyaitR+E3FAFL/d0Msx/8VwAXriNN7u+NInA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O6MJSTtPwr+xyhNkhNg+G/A+hFhKPeL7PY/2qqy5QCkAJQA6bHfXdhcVAe535BxR7 KcfI9lahOTKcnwSdjKs/vXYXtqYOys5vG3jEFbmeW45OaG2SxCStOvcnGBq2FRYFCP dtq2A9IQW+BG1YO/wpe2AsjYNgH1DDObvFRgnAGI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com, Qianqiang Liu , Helge Deller , Sasha Levin Subject: [PATCH 6.11 078/214] fbcon: Fix a NULL pointer dereference issue in fbcon_putcs Date: Mon, 14 Oct 2024 16:19:01 +0200 Message-ID: <20241014141048.032995402@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241014141044.974962104@linuxfoundation.org> References: <20241014141044.974962104@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.11-stable review patch. If anyone has any objections, please let me know. ------------------ 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 3f7333dca508c..fedd796c9a5cd 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