netdev - Re: [PATCH v4] net: don't call strlen() on the user buffer in packet_bind

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Message-Id: <20170301.205752.2006881054868352173.davem@davemloft.net>
Date:   Wed, 01 Mar 2017 20:57:52 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     glider@...gle.com
Cc:     dvyukov@...gle.com, kcc@...gle.com, edumazet@...gle.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v4] net: don't call strlen() on the user buffer in
 packet_bind_spkt()

From: Alexander Potapenko <glider@...gle.com>
Date: Wed,  1 Mar 2017 12:57:20 +0100

> KMSAN (KernelMemorySanitizer, a new error detection tool) reports use of
> uninitialized memory in packet_bind_spkt():
 ...
> This happens because addr.sa_data copied from the userspace is not
> zero-terminated, and copying it with strlcpy() in packet_bind_spkt()
> results in calling strlen() on the kernel copy of that non-terminated
> buffer.
> 
> Signed-off-by: Alexander Potapenko <glider@...gle.com>
> ---
> Changes since v3:
>  - addressed comments by Eric Dumazet (avoid using constants,
>    use memcpy() instead of strncpy())

Applied and queued up for -stable.