netdev - Re: [PATCH bpf] bpf, ppc64: fix out of bounds access in tail call

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Date:   Mon, 26 Feb 2018 19:59:06 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     ast@...nel.org, naveen.n.rao@...ux.vnet.ibm.com,
        netdev@...r.kernel.org
Subject: Re: [PATCH bpf] bpf, ppc64: fix out of bounds access in tail call

On Mon, Feb 26, 2018 at 10:00:47PM +0100, Daniel Borkmann wrote:
> While working on 16338a9b3ac3 ("bpf, arm64: fix out of bounds access in
> tail call") I noticed that ppc64 JIT is partially affected as well. While
> the bound checking is correctly performed as unsigned comparison, the
> register with the index value however, is never truncated into 32 bit
> space, so e.g. a index value of 0x100000000ULL with a map of 1 element
> would pass with PPC_CMPLW() whereas we later on continue with the full
> 64 bit register value. Therefore, as we do in interpreter and other JITs
> truncate the value to 32 bit initially in order to fix access.
> 
> Fixes: ce0761419fae ("powerpc/bpf: Implement support for tail calls")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Reviewed-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
> Tested-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>

Applied to bpf tree, thanks Daniel.