netdev - RE: [PATCH 6/9] x86/bpf: Fix JIT frame pointer usage

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]

Date:   Fri, 14 Jun 2019 10:50:23 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Alexei Starovoitov' <alexei.starovoitov@...il.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>
CC:     "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        "Daniel Borkmann" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        Song Liu <songliubraving@...com>,
        "Kairui Song" <kasong@...hat.com>
Subject: RE: [PATCH 6/9] x86/bpf: Fix JIT frame pointer usage

On Thu, Jun 13, 2019 at 08:21:03AM -0500, Josh Poimboeuf wrote:
> The BPF JIT code clobbers RBP.  This breaks frame pointer convention and
> thus prevents the FP unwinder from unwinding through JIT generated code.
>
> RBP is currently used as the BPF stack frame pointer register.  The
> actual register used is opaque to the user, as long as it's a
> callee-saved register.  Change it to use R12 instead.

Could you maintain the system %rbp chain through the BPF stack?
It might even be possible to put something relevant in the %rip
location.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)