From: Suren Baghdasaryan <surenb@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Eric Biggers <ebiggers@kernel.org>, Tejun Heo <tj@kernel.org>,
Zefan Li <lizefan.x@bytedance.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Benjamin Segall <bsegall@google.com>,
Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
cgroups mailinglist <cgroups@vger.kernel.org>,
stable <stable@vger.kernel.org>,
kernel-team <kernel-team@android.com>,
syzbot <syzbot+cdb5dd11c97cc532efad@syzkaller.appspotmail.com>
Subject: Re: [PATCH v3 1/1] psi: Fix uaf issue when psi trigger is destroyed while being polled
Date: Wed, 12 Jan 2022 10:26:08 -0800 [thread overview]
Message-ID: <CAJuCfpF45VY_7esx7p2yEK+eK-ufSMsBETEdJPF=Mzxj+BTnLA@mail.gmail.com> (raw)
In-Reply-To: <Yd8a8TdThrGHsf2o@casper.infradead.org>
On Wed, Jan 12, 2022 at 10:16 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Wed, Jan 12, 2022 at 09:49:00AM -0800, Suren Baghdasaryan wrote:
> > > This happens with the following config:
> > >
> > > CONFIG_CGROUPS=n
> > > CONFIG_PSI=y
> > >
> > > With cgroups disabled these functions are defined as non-static but
> > > are not defined in the header
> > > (https://elixir.bootlin.com/linux/latest/source/include/linux/psi.h#L28)
> > > since the only external user cgroup.c is disabled. The cleanest way to
> > > fix these I think is by doing smth like this in psi.c:
>
> A cleaner way to solve these is simply:
>
> #ifndef CONFIG_CGROUPS
> static struct psi_trigger *psi_trigger_create(...);
> ...
> #endif
>
> I tested this works:
>
> $ cat foo5.c
> static int psi(void *);
>
> int psi(void *x)
> {
> return (int)(long)x;
> }
>
> int bar(void *x)
> {
> return psi(x);
> }
> $ gcc -W -Wall -O2 -c -o foo5.o foo5.c
> $ readelf -s foo5.o
>
> Symbol table '.symtab' contains 4 entries:
> Num: Value Size Type Bind Vis Ndx Name
> 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
> 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS foo5.c
> 2: 0000000000000000 0 SECTION LOCAL DEFAULT 1 .text
> 3: 0000000000000000 3 FUNC GLOBAL DEFAULT 1 bar
>
Thanks Matthew!
That looks much cleaner. I'll post a separate patch to fix these. My
main concern was whether it's worth adding more code to satisfy this
warning but with this approach the code changes are minimal, so I'll
go ahead and post it shortly.
WARNING: multiple messages have this Message-ID (diff)
From: Suren Baghdasaryan <surenb@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Eric Biggers <ebiggers@kernel.org>, Tejun Heo <tj@kernel.org>,
Zefan Li <lizefan.x@bytedance.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Benjamin Segall <bsegall@google.com>,
Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
cgroups mailinglist <cgroups@vger.kernel.org>,
stable <stable@vger.kernel.org>,
kernel-t
Subject: Re: [PATCH v3 1/1] psi: Fix uaf issue when psi trigger is destroyed while being polled
Date: Wed, 12 Jan 2022 10:26:08 -0800 [thread overview]
Message-ID: <CAJuCfpF45VY_7esx7p2yEK+eK-ufSMsBETEdJPF=Mzxj+BTnLA@mail.gmail.com> (raw)
In-Reply-To: <Yd8a8TdThrGHsf2o@casper.infradead.org>
On Wed, Jan 12, 2022 at 10:16 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Wed, Jan 12, 2022 at 09:49:00AM -0800, Suren Baghdasaryan wrote:
> > > This happens with the following config:
> > >
> > > CONFIG_CGROUPS=n
> > > CONFIG_PSI=y
> > >
> > > With cgroups disabled these functions are defined as non-static but
> > > are not defined in the header
> > > (https://elixir.bootlin.com/linux/latest/source/include/linux/psi.h#L28)
> > > since the only external user cgroup.c is disabled. The cleanest way to
> > > fix these I think is by doing smth like this in psi.c:
>
> A cleaner way to solve these is simply:
>
> #ifndef CONFIG_CGROUPS
> static struct psi_trigger *psi_trigger_create(...);
> ...
> #endif
>
> I tested this works:
>
> $ cat foo5.c
> static int psi(void *);
>
> int psi(void *x)
> {
> return (int)(long)x;
> }
>
> int bar(void *x)
> {
> return psi(x);
> }
> $ gcc -W -Wall -O2 -c -o foo5.o foo5.c
> $ readelf -s foo5.o
>
> Symbol table '.symtab' contains 4 entries:
> Num: Value Size Type Bind Vis Ndx Name
> 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
> 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS foo5.c
> 2: 0000000000000000 0 SECTION LOCAL DEFAULT 1 .text
> 3: 0000000000000000 3 FUNC GLOBAL DEFAULT 1 bar
>
Thanks Matthew!
That looks much cleaner. I'll post a separate patch to fix these. My
main concern was whether it's worth adding more code to satisfy this
warning but with this approach the code changes are minimal, so I'll
go ahead and post it shortly.
next prev parent reply other threads:[~2022-01-12 18:26 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-11 23:23 [PATCH v3 1/1] psi: Fix uaf issue when psi trigger is destroyed while being polled Suren Baghdasaryan
2022-01-12 6:46 ` Eric Biggers
2022-01-12 10:03 ` Peter Zijlstra
2022-01-12 18:03 ` Linus Torvalds
2022-01-12 18:03 ` Linus Torvalds
2022-01-12 14:39 ` Johannes Weiner
2022-01-12 17:43 ` Suren Baghdasaryan
2022-01-12 17:43 ` Suren Baghdasaryan
2022-01-12 17:49 ` Suren Baghdasaryan
2022-01-12 17:49 ` Suren Baghdasaryan
2022-01-12 18:16 ` Matthew Wilcox
2022-01-12 18:16 ` Matthew Wilcox
2022-01-12 18:26 ` Suren Baghdasaryan [this message]
2022-01-12 18:26 ` Suren Baghdasaryan
2022-01-12 18:44 ` Eric Biggers
2022-01-12 18:44 ` Eric Biggers
2022-01-12 18:53 ` Suren Baghdasaryan
2022-01-12 18:53 ` Suren Baghdasaryan
2022-01-12 19:04 ` Eric Biggers
2022-01-12 19:04 ` Eric Biggers
2022-01-12 19:06 ` Suren Baghdasaryan
2022-01-12 19:06 ` Suren Baghdasaryan
2022-01-12 19:49 ` Suren Baghdasaryan
2022-01-12 19:49 ` Suren Baghdasaryan
2022-01-12 15:18 ` kernel test robot
2022-01-12 16:39 ` kernel test robot
2022-01-12 16:39 ` kernel test robot
2022-01-18 11:18 ` [tip: sched/urgent] " tip-bot2 for Suren Baghdasaryan
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