netdev - Re: [PATCH net] bpf: fix 64-bit divide

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Message-Id: <20150427.231514.208514856523229950.davem@davemloft.net>
Date:	Mon, 27 Apr 2015 23:15:14 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	ast@...mgrid.com
Cc:	daniel@...earbox.net, holzheu@...ux.vnet.ibm.com,
	netdev@...r.kernel.org
Subject: Re: [PATCH net] bpf: fix 64-bit divide

From: Alexei Starovoitov <ast@...mgrid.com>
Date: Mon, 27 Apr 2015 14:40:37 -0700

> ALU64_DIV instruction should be dividing 64-bit by 64-bit,
> whereas do_div() does 64-bit by 32-bit divide.
> x64 and arm64 JITs correctly implement 64 by 64 unsigned divide.
> llvm BPF backend emits code assuming that ALU64_DIV does 64 by 64.
> 
> Fixes: 89aa075832b0 ("net: sock: allow eBPF programs to be attached to sockets")
> Reported-by: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
> Acked-by: Daniel Borkmann <daniel@...earbox.net>
> Signed-off-by: Alexei Starovoitov <ast@...mgrid.com>
> ---
> The bug is old and sneaked in during the very first eBPF code drop:
> Fixes: bd4cf0ed331a ("net: filter: rework/optimize internal BPF interpreter's instruction set")
> but it's not affecting classic and shouldn't be backported further
> than commit 89aa075832b0 (which is the above Fixes tag).
> It was found by exhaustive tests being written by Michael Holzheu.

Ok, applied and queued up for v3.19 -stable and later.

Thanks.
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