From: Peter Zijlstra <peterz@infradead.org>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Fengguang Wu <fengguang.wu@intel.com>,
linux-kernel@vger.kernel.org, Wang Nan <wangnan0@huawei.com>,
Ingo Molnar <mingo@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Will Deacon <will.deacon@arm.com>,
lkp@01.org, Dmitry Vyukov <dvyukov@google.com>,
kasan-dev@googlegroups.com, kernel-team@lge.com
Subject: Re: BUG: KASAN: slab-out-of-bounds in perf_callchain_user+0x494/0x530
Date: Wed, 6 Dec 2017 16:45:44 +0100 [thread overview]
Message-ID: <20171206154544.oiavdgfrpryak23z@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20171206143130.GA3367@danjae.aot.lge.com>
On Wed, Dec 06, 2017 at 11:31:30PM +0900, Namhyung Kim wrote:
> > There's also a race against put_callchain_buffers() there, consider:
> >
> >
> > get_callchain_buffers() put_callchain_buffers()
> > mutex_lock();
> > inc()
> > dec_and_test() // false
> >
> > dec() // 0
> >
> >
> > And the buffers leak.
>
> Hmm.. did you mean that get_callchain_buffers() returns an error?
Yes, get_callchain_buffers() fails, but while doing so it has a
temporary increment on the count.
> AFAICS it cannot fail when it sees count > 1 (and callchain_cpus_
> entries is allocated).
It can with your patch. We only test event_max_stack against the sysctl
after incrementing.
next prev parent reply other threads:[~2017-12-06 15:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-30 2:32 BUG: KASAN: slab-out-of-bounds in perf_callchain_user+0x494/0x530 Fengguang Wu
2017-11-30 8:20 ` Peter Zijlstra
2017-11-30 19:37 ` Arnaldo Carvalho de Melo
2017-12-05 8:11 ` Namhyung Kim
2017-12-05 13:37 ` Arnaldo Carvalho de Melo
2017-12-05 14:47 ` Namhyung Kim
2017-12-06 13:47 ` Peter Zijlstra
2017-12-06 14:12 ` Arnaldo Carvalho de Melo
2017-12-06 14:31 ` Namhyung Kim
2017-12-06 15:45 ` Peter Zijlstra [this message]
2017-12-06 15:49 ` Namhyung Kim
2017-12-06 16:39 ` Peter Zijlstra
2017-12-06 15:46 ` Namhyung Kim
2017-12-06 13:40 ` Peter Zijlstra
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