linux-kernel - Re: [REGRESSION] x86/entry: TIF_SINGLESTEP handling is still broken

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <0456DEB3-2EA6-4CA6-AA59-E5E1D8F1A77A@amacapital.net>
Date:   Sun, 31 Jan 2021 14:04:44 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Kyle Huey <me@...ehuey.com>, Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        open list <linux-kernel@...r.kernel.org>,
        Robert O'Callahan <rocallahan@...il.com>
Subject: Re: [REGRESSION] x86/entry: TIF_SINGLESTEP handling is still broken



> On Jan 31, 2021, at 1:30 PM, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> 
> Btw Kyle, do you have a good simple test-case for this? Clearly this
> is some weird special case use, and regular single-stepping works
> fine.
> 
> 

Indeed, and I have tests for this.

TBH, the TIF_SINGLESTEP code makes no sense, and I think it has at least three overloaded meanings. I can try to look in a bit.  I’ve mostly avoided breaking it in the past, but that doesn’t mean I understand the original intent.