Re: [syzbot] WARNING in ex_handler_fprestore

From: Andy Lutomirski
Date: Tue May 25 2021 - 20:33:32 EST


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?