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Subject: Re: [PATCH] bpf: explicitly memset the bpf_attr structure
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Alexei Starovoitov <ast@kernel.org>
Cc:     Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
        Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
        netdev@vger.kernel.org, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        =?UTF-8?Q?Maciej_=c5=bbenczykowski?= <maze@google.com>,
        John Stultz <john.stultz@linaro.org>,
        Alexander Potapenko <glider@google.com>,
        Alistair Delva <adelva@google.com>
References: <20200320094813.GA421650@kroah.com>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <cea7babd-48a6-d89a-c93b-32659d6d8a28@iogearbox.net>
Date:   Fri, 20 Mar 2020 21:07:24 +0100
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On 3/20/20 10:48 AM, Greg Kroah-Hartman wrote:
> For the bpf syscall, we are relying on the compiler to properly zero out
> the bpf_attr union that we copy userspace data into.  Unfortunately that
> doesn't always work properly, padding and other oddities might not be
> correctly zeroed, and in some tests odd things have been found when the
> stack is pre-initialized to other values.
> 
> Fix this by explicitly memsetting the structure to 0 before using it.
> 
> Reported-by: Maciej Żenczykowski <maze@google.com>
> Reported-by: John Stultz <john.stultz@linaro.org>
> Reported-by: Alexander Potapenko <glider@google.com>
> Reported-by: Alistair Delva <adelva@google.com>
> Cc: stable <stable@vger.kernel.org>
> Link: https://android-review.googlesource.com/c/kernel/common/+/1235490
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Applied, thanks!