linux-kernel - Re: [PATCH RFC v3 02/10] sched_getattr: port to copy_struct_to

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: <82ee186ae5580548fe6b0edd2720359c18f6fa9a.camel@xry111.site>
Date: Sat, 18 Jan 2025 21:02:54 +0800
From: Xi Ruoyao <xry111@...111.site>
To: Christian Brauner <brauner@...nel.org>, Florian Weimer
 <fweimer@...hat.com>,  Aleksa Sarai <cyphar@...har.com>, Ingo Molnar
 <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Juri Lelli
 <juri.lelli@...hat.com>,  Vincent Guittot <vincent.guittot@...aro.org>,
 Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt	
 <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman	
 <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>, Alexander Viro
	 <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, Arnd Bergmann
 <arnd@...db.de>,  Shuah Khan <shuah@...nel.org>, Kees Cook
 <kees@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, linux-arch@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, libc-alpha@...rceware.org
Subject: Re: [PATCH RFC v3 02/10] sched_getattr: port to copy_struct_to_user

On Wed, 2024-12-11 at 11:23 +0100, Christian Brauner wrote:
> On Tue, Dec 10, 2024 at 07:14:07PM +0100, Florian Weimer wrote:
> > * Aleksa Sarai:
> > 
> > > sched_getattr(2) doesn't care about trailing non-zero bytes in the
> > > (ksize > usize) case, so just use copy_struct_to_user() without checking
> > > ignored_trailing.
> > 
> > I think this is what causes glibc's misc/tst-sched_setattr test to fail
> > on recent kernels.  The previous non-modifying behavior was documented
> > in the manual page:
> > 
> >        If the caller-provided attr buffer is larger than the kernel's
> >        sched_attr structure, the additional bytes in the user-space
> >        structure are not touched.
> > 
> > I can just drop this part of the test if the kernel deems both behaviors
> > valid.

> I think in general both behaviors are valid but I would consider zeroing
> the unknown parts of the provided buffer to be the safer option. And all
> newer extensible struct system calls do that.

Florian,

So should we drop the test before Glibc-2.41 release?  I'm seeing the
failure during my machine test.

-- 
Xi Ruoyao <xry111@...111.site>
School of Aerospace Science and Technology, Xidian University