linux-kernel - Re: [syzbot] BUG: unable to handle kernel paging request in vga16fb

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Date:   Mon, 30 Aug 2021 23:38:22 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        syzbot <syzbot+04168c8063cfdde1db5e@...kaller.appspotmail.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Colin King <colin.king@...onical.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] BUG: unable to handle kernel paging request in
 vga16fb_fillrect

On 2021/08/30 23:30, Geert Uytterhoeven wrote:
> The highest possible value of maxmem inside vga16fb_check_var()
> is 65536.

Yes.

> 
> So I believe
> 
>     if (array_size(vxres, vyres) > maxmem)
> 
> should work fine.

My intent is to check at common path than individual module so that we don't
need to add same check to every module. Same approach is proposed at
https://lkml.kernel.org/r/1630294223-7225-1-git-send-email-tcs_kernel@tencent.com .