linux-kernel - Re: [syzbot] WARNING in ex_handler

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Message-ID: <fe20f360-7c6c-f1bf-c3a5-403ae979fae6@kernel.org>
Date:   Tue, 25 May 2021 17:33:25 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     syzbot <syzbot+2067e764dbcd10721e2e@...kaller.appspotmail.com>,
        bp@...en8.de, bp@...e.de, dave.hansen@...ux.intel.com,
        fenghua.yu@...el.com, hpa@...or.com, linux-kernel@...r.kernel.org,
        mingo@...hat.com, peterz@...radead.org,
        syzkaller-bugs@...glegroups.com, tglx@...utronix.de,
        tony.luck@...el.com, x86@...nel.org, yu-cheng.yu@...el.com
Subject: Re: [syzbot] WARNING in ex_handler_fprestore

On 5/24/21 1:51 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    45af60e7 Merge tag 'for-5.13-rc2-tag' of git://git.kernel...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1591e9f7d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=18fade5827eb74f7
> dashboard link: https://syzkaller.appspot.com/bug?extid=2067e764dbcd10721e2e
> compiler:       Debian clang version 11.0.1-2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11be6bd1d00000

Hi syz people and x86 people-

I entirely believe that this bug is real and that syzbot bisected it
correctly, but I'm puzzled by the reproducer.  It says:

ptrace$setregs(0xd, r0, 0x0, &(0x7f0000000080))

I would really, really expect this to result from PTRACE_SETREGSET or
PTRACE_SETFPREGS, but this is PTRACE_SETREGS.


Am I missing something really obvious here?