linux-kernel - Re: [PATCH 02/18] vchecker: introduce the valid access checker

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Date:   Tue, 28 Nov 2017 11:41:08 -0800
From:   Andi Kleen <ak@...ux.intel.com>
To:     js1304@...il.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Namhyung Kim <namhyung@...nel.org>,
        Wengang Wang <wen.gang.wang@...cle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH 02/18] vchecker: introduce the valid access checker

js1304@...il.com writes:

> From: Joonsoo Kim <iamjoonsoo.kim@....com>

Looks useful. Essentially unlimited hardware break points, combined
with slab.

Didn't do a full review, but noticed some things below.
> +
> +	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	if (copy_from_user(buf, ubuf, cnt)) {
> +		kfree(buf);
> +		return -EFAULT;
> +	}
> +
> +	if (isspace(buf[0]))
> +		remove = true;

and that may be uninitialized.

and the space changes the operation? That's a strange syntax.


> +	buf[cnt - 1] = '\0';

That's an underflow of one byte if cnt is 0.


-Andi