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From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Kan Liang <kan.liang@linux.intel.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	"Liam R . Howlett" <Liam.Howlett@oracle.com>,
	Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
	linux-mm@kvack.org, Peng Zhang <zhangpeng.00@bytedance.com>
Subject: Re: [PATCH] fork: avoid inappropriate uprobe access to invalid mm
Date: Tue, 10 Dec 2024 17:01:34 +0000	[thread overview]
Message-ID: <38d54e6f-54cf-49b0-b879-4fc4a2afc749@lucifer.local> (raw)
In-Reply-To: <20241210165334.GB31266@redhat.com>

On Tue, Dec 10, 2024 at 05:53:34PM +0100, Oleg Nesterov wrote:
> I must have missed something, but...
>
> On 12/10, Lorenzo Stoakes wrote:
> >
> > @@ -1746,9 +1741,11 @@ static struct mm_struct *dup_mm(struct task_struct *tsk,
> >  	if (!mm_init(mm, tsk, mm->user_ns))
> >  		goto fail_nomem;
> >
> > +	uprobe_start_dup_mmap();
> >  	err = dup_mmap(mm, oldmm);
> >  	if (err)
> > -		goto free_pt;
> > +		goto free_pt_end_uprobe;
> > +	uprobe_end_dup_mmap();
> >
> >  	mm->hiwater_rss = get_mm_rss(mm);
> >  	mm->hiwater_vm = mm->total_vm;
> > @@ -1758,6 +1755,8 @@ static struct mm_struct *dup_mm(struct task_struct *tsk,
> >
> >  	return mm;
> >
> > +free_pt_end_uprobe:
> > +	uprobe_end_dup_mmap();
>
> if dup_mmap() fails and "mm" is incomplete, then with this version dup_mmap_sem
> is dropped before __mmput/exit_mmap/etc. How can this help?

Doh! Sorry, this is me rather rushing through this aspect of it here, my
mistake... I may risk an immmediate v2 with apologies to all for the noise... :P

>
> Oleg.
>


  reply	other threads:[~2024-12-10 17:02 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-10 16:31 Lorenzo Stoakes
2024-12-10 16:53 ` Oleg Nesterov
2024-12-10 17:01   ` Lorenzo Stoakes [this message]
2024-12-10 17:23   ` Oleg Nesterov
2024-12-10 17:34     ` Lorenzo Stoakes

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