linux-kernel - Re: general protection fault in syscall_return

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Date:   Sun, 8 Mar 2020 09:29:04 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     syzbot <syzbot+cd66e43794b178bb5cd6@...kaller.appspotmail.com>
Cc:     Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        syzkaller-bugs@...glegroups.com,
        Thomas Gleixner <tglx@...utronix.de>, X86 ML <x86@...nel.org>
Subject: Re: general protection fault in syscall_return_slowpath

On Sat, Mar 7, 2020 at 11:45 PM syzbot
<syzbot+cd66e43794b178bb5cd6@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    63623fd4 Merge tag 'for-linus' of git://git.kernel.org/pub..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16cfeac3e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5d2e033af114153f
> dashboard link: https://syzkaller.appspot.com/bug?extid=cd66e43794b178bb5cd6
> compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12a42329e00000
>

I bet this is due to entirely missing input validation in
con_font_copy() and/or fbcon_copy_font().