linux-kernel - Re: [PATCH -next v2] uprobes: fix two zero old_folio bugs in __replace

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Message-ID: <20250221152841.GA24705@redhat.com>
Date: Fri, 21 Feb 2025 16:28:41 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Tong Tiangen <tongtiangen@...wei.com>
Cc: David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Peter Xu <peterx@...hat.com>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, linux-trace-kernel@...r.kernel.org,
	bpf@...r.kernel.org, wangkefeng.wang@...wei.com,
	Guohanjun <guohanjun@...wei.com>
Subject: Re: [PATCH -next v2] uprobes: fix two zero old_folio bugs in
 __replace_page()

On 02/21, Tong Tiangen wrote:
>
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -506,6 +506,11 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
>  	if (ret <= 0)
>  		goto put_old;
>
> +	if (is_zero_page(old_page)) {
> +		ret = -EINVAL;
> +		goto put_old;
> +	}

I agree with David, the subject looks a bit misleading.

And. I won't insist, this is cosmetic, but if you send V2 please consider
moving the "verify_opcode()" check down, after the is_zero_page/PageCompound
checks.

Oleg.