linux-hardening - Re: [PATCH v2 1/5] string.h: add array-wrappers for (v)memdup

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Message-ID: <b219788a-69e6-44cf-a609-91f9640967f5@moroto.mountain>
Date:   Sat, 16 Sep 2023 17:32:42 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Philipp Stanner <pstanner@...hat.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Andy Shevchenko <andy@...nel.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Christian Brauner <brauner@...nel.org>,
        David Disseldorp <ddiss@...e.de>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Siddh Raman Pant <code@...dh.me>,
        Nick Alcock <nick.alcock@...cle.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, Zack Rusin <zackr@...are.com>,
        VMware Graphics Reviewers 
        <linux-graphics-maintainer@...are.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org, linux-hardening@...r.kernel.org,
        David Airlie <airlied@...hat.com>
Subject: Re: [PATCH v2 1/5] string.h: add array-wrappers for (v)memdup_user()

On Fri, Sep 08, 2023 at 09:59:40PM +0200, Philipp Stanner wrote:
> +static inline void *memdup_array_user(const void __user *src, size_t n, size_t size)
> +{
> +	size_t nbytes;
> +
> +	if (unlikely(check_mul_overflow(n, size, &nbytes)))
> +		return ERR_PTR(-EOVERFLOW);

No need for an unlikely() because check_mul_overflow() already has one
inside.  I feel like -ENOMEM is more traditional but I doubt anyone/userspace
cares.

> +
> +	return memdup_user(src, nbytes);
> +}

regards,
dan carpenter