linux-kernel - Re: [PATCH v4 1/4] powerpc: make llseek 32bit-only.

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: <20190829161923.101ff3eb@kitsune.suse.cz>
Date:   Thu, 29 Aug 2019 16:19:23 +0200
From:   Michal Suchánek <msuchanek@...e.de>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Michael Neuling <mikey@...ling.org>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Nicolai Stange <nstange@...e.de>,
        David Hildenbrand <david@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        David Howells <dhowells@...hat.com>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Paul Mackerras <paulus@...ba.org>,
        Joel Stanley <joel@....id.au>,
        Christian Brauner <christian@...uner.io>,
        Firoz Khan <firoz.khan@...aro.org>,
        Breno Leitao <leitao@...ian.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Allison Randal <allison@...utok.net>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH v4 1/4] powerpc: make llseek 32bit-only.

On Thu, 29 Aug 2019 14:57:39 +0200
Arnd Bergmann <arnd@...db.de> wrote:

> On Thu, Aug 29, 2019 at 2:37 PM Michal Suchánek <msuchanek@...e.de> wrote:
> > On Thu, 29 Aug 2019 14:19:46 +0200 Arnd Bergmann <arnd@...db.de> wrote:  
> > > On Thu, Aug 29, 2019 at 12:23 PM Michal Suchanek <msuchanek@...e.de> wrote:
> > > In particular, I don't see why you single out llseek here, but leave other
> > > syscalls that are not needed on 64-bit machines such as pread64().  
> >
> > Because llseek is not built in fs/ when building 64bit only causing a
> > link error.
> >
> > I initially posted patch to build it always but it was pointed out it
> > is not needed, and  the interface does not make sense on 64bit, and
> > that platforms that don't have it on 64bit now don't want that useless
> > code.  
> 
> Ok, please put that into the changeset description then.
> 
> I looked at uses of __NR__llseek in debian code search and
> found this one:
> 
> https://codesearch.debian.net/show?file=umview_0.8.2-1.2%2Fxmview%2Fum_mmap.c&line=328
> 
> It looks like this application will try to use llseek instead of lseek
> when built against kernel headers that define __NR_llseek.
> 

The available documentation says this syscall is for 32bit only so
using it on 64bit is undefined. The interface is not well-defined in
that case either.

Thanks

Michal