From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF319C432BE for ; Thu, 2 Sep 2021 13:15:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 94C21610A0 for ; Thu, 2 Sep 2021 13:15:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234054AbhIBNQi (ORCPT ); Thu, 2 Sep 2021 09:16:38 -0400 Received: from mail-vk1-f171.google.com ([209.85.221.171]:45908 "EHLO mail-vk1-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244365AbhIBNQe (ORCPT ); Thu, 2 Sep 2021 09:16:34 -0400 Received: by mail-vk1-f171.google.com with SMTP id h13so597331vkc.12; Thu, 02 Sep 2021 06:15:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=97U7yjyC9u7K560fHPV0AzvZLQ1JtD7v4r1SnsrSUGw=; b=G1yN86/PcmtMQIxqQ1SH2PVic7yweUn0FPrNVmeWWsAciPys7w0TUzFviD/Ri7wcqV Z+TbkBnbDtQy6aqtYGYvKtrkJkLSkKJd9AdHOfllZUPI2IAv7OVUv0BLyvn/s4gkQtVp 8IrXMccbmMKDwv/O6IbbbgPLcMNA4heUM6gEAXVvTpTzlm9B+vWrhE5cl9LcfCDZ28fW VegICkSHE0W69va4CDOX8ko9h6y6bFfi02rxrAOw1TddEKOaL8tXAElAkhERycWa5/jH jv16G1xjuX2+oTdh/u1u6LKq//YFBYJT9C7VVoWYW6ouMXUezC+voNgxHJuG5VigGgu7 cmQQ== X-Gm-Message-State: AOAM532Ehp08nCAqKsx9on35GKU20SviDeFVeGuopBBSzrNoRgaCRzXD JJj8UwalYe0L5QzUwQGkL258s3VO4cAj0ke97+Y= X-Google-Smtp-Source: ABdhPJyQfNHd8eekTjjRF+Djs44a/sSv6U+YNBayDddfjAvJLpLh7J03k+WxXm3fVzYEOjiv/xorOOUMd/FOKfZUqC4= X-Received: by 2002:a1f:bd0a:: with SMTP id n10mr1537493vkf.5.1630588535725; Thu, 02 Sep 2021 06:15:35 -0700 (PDT) MIME-Version: 1.0 References: <20210902060213.1702544-1-mudongliangabcd@gmail.com> In-Reply-To: <20210902060213.1702544-1-mudongliangabcd@gmail.com> From: Geert Uytterhoeven Date: Thu, 2 Sep 2021 15:15:24 +0200 Message-ID: Subject: Re: [PATCH 4.19] fbmem: add margin check to fb_check_caps() To: Dongliang Mu Cc: Bartlomiej Zolnierkiewicz , George Kennedy , syzbot+e5fd3e65515b48c02a30@syzkaller.appspotmail.com, Dan Carpenter , Dhaval Giani , Sasha Levin , DRI Development , Linux Fbdev development list , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dongliang, On Thu, Sep 2, 2021 at 8:04 AM Dongliang Mu wrote: > [ Upstream commit a49145acfb975d921464b84fe00279f99827d816 ] Oops, looks like I missed when that one was submitted for review... > A fb_ioctl() FBIOPUT_VSCREENINFO call with invalid xres setting > or yres setting in struct fb_var_screeninfo will result in a > KASAN: vmalloc-out-of-bounds failure in bitfill_aligned() as > the margins are being cleared. The margins are cleared in > chunks and if the xres setting or yres setting is a value of > zero upto the chunk size, the failure will occur. > > Add a margin check to validate xres and yres settings. Shouldn't (the caller of) bitfill_aligned() be fixed instead? Can this be triggered by e.g. using the mini_4x6 font? > Note that, this patch needs special handling to backport it to linux > kernel 4.19, 4.14, 4.9, 4.4. > > Signed-off-by: George Kennedy > Reported-by: syzbot+e5fd3e65515b48c02a30@syzkaller.appspotmail.com > Reviewed-by: Dan Carpenter > Cc: Dhaval Giani > Signed-off-by: Bartlomiej Zolnierkiewicz > Link: https://patchwork.freedesktop.org/patch/msgid/1594149963-13801-1-git-send-email-george.kennedy@oracle.com > Signed-off-by: Sasha Levin > --- > drivers/video/fbdev/core/fbmem.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c > index 84845275dbef..de04c097d67c 100644 > --- a/drivers/video/fbdev/core/fbmem.c > +++ b/drivers/video/fbdev/core/fbmem.c > @@ -991,6 +991,10 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) > goto done; > } > > + /* bitfill_aligned() assumes that it's at least 8x8 */ > + if (var->xres < 8 || var->yres < 8) > + return -EINVAL; Are you sure there don't exist such small displays (e.g. OLED)? > + > ret = info->fbops->fb_check_var(var, info); > > if (ret) Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds