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From: Florian Weimer <fweimer@redhat.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, jannh@google.com,
	keescook@chromium.org, jeffv@google.com, minchan@kernel.org,
	mhocko@suse.com, shakeelb@google.com, rientjes@google.com,
	edgararriaga@google.com, timmurray@google.com,
	linux-mm@kvack.org, selinux@vger.kernel.org,
	linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@android.com
Subject: Re: [PATCH 1/1] mm/madvise: replace ptrace attach requirement for process_madvise
Date: Mon, 11 Jan 2021 11:20:01 +0100	[thread overview]
Message-ID: <875z43rd0u.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <20210108205857.1471269-1-surenb@google.com> (Suren Baghdasaryan's message of "Fri, 8 Jan 2021 12:58:57 -0800")

* Suren Baghdasaryan:

> diff --git a/mm/madvise.c b/mm/madvise.c
> index 6a660858784b..c2d600386902 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -1197,12 +1197,22 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
>  		goto release_task;
>  	}
>  
> -	mm = mm_access(task, PTRACE_MODE_ATTACH_FSCREDS);
> +	/* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
> +	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
>  	if (IS_ERR_OR_NULL(mm)) {
>  		ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
>  		goto release_task;
>  	}

Shouldn't this depend on the requested behavior?  Several operations
directly result in observable changes, and go beyond performance tuning.

Thanks,
Florian
-- 
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  parent reply	other threads:[~2021-01-11 10:21 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-08 20:58 [PATCH 1/1] mm/madvise: replace ptrace attach requirement for process_madvise Suren Baghdasaryan
2021-01-08 22:15 ` Minchan Kim
2021-01-08 22:17   ` Suren Baghdasaryan
2021-01-09  1:02     ` David Rientjes
2021-01-09  2:19       ` Suren Baghdasaryan
2021-01-11 10:20 ` Florian Weimer [this message]
2021-01-11 17:05   ` Suren Baghdasaryan
2021-01-11 17:09     ` Suren Baghdasaryan

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