From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subject: Re: [net PATCH] bpf: devmap fix arithmetic overflow in bitmap_size
 calculation
Date: Thu, 19 Oct 2017 15:12:46 -0700
Message-ID: <20171019221245.a7grq3csbpixjgpn@ast-mbp>
References: <150842903200.12537.10765604428561566031.stgit@john-XPS-13-9360>
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Cc: richard@nod.at, davem@davemloft.net, netdev@vger.kernel.org,
        borkmann@iogearbox.net
To: John Fastabend <john.r.fastabend@gmail.com>
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On Thu, Oct 19, 2017 at 09:03:52AM -0700, John Fastabend wrote:
> An integer overflow is possible in dev_map_bitmap_size() when
> calculating the BITS_TO_LONG logic which becomes, after macro
> replacement,
> 
> 	(((n) + (d) - 1)/ (d))
> 
> where 'n' is a __u32 and 'd' is (8 * sizeof(long)). To avoid
> overflow cast to u64 before arithmetic.
> 
> Reported-by: Richard Weinberger <richard@nod.at>
> Acked-by: Daniel Borkmann <daniel@iogearbox.net>
> Signed-off-by: John Fastabend <john.fastabend@gmail.com>

Acked-by: Alexei Starovoitov <ast@kernel.org>