linux-kernel - Re: [PATCH v2] arm: eBPF JIT compiler

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170612110611.GC4902@n2100.armlinux.org.uk>
Date:   Mon, 12 Jun 2017 12:06:11 +0100
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Kees Cook <keescook@...omium.org>,
        Shubham Bansal <illusionist.neo@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH v2] arm: eBPF JIT compiler

On Mon, Jun 12, 2017 at 12:21:03PM +0200, Daniel Borkmann wrote:
> On 05/30/2017 09:19 PM, Kees Cook wrote:
> >On Thu, May 25, 2017 at 4:13 PM, Shubham Bansal
> ><illusionist.neo@...il.com> wrote:
> >>+static int validate_code(struct jit_ctx *ctx)
> >>+{
> >>+       int i;
> >>+
> >>+       for (i = 0; i < ctx->idx; i++) {
> >>+               u32 a32_insn = le32_to_cpu(ctx->target[i]);
> 
> Given __opcode_to_mem_arm(ARM_INST_UDF) is used to fill the image,
> perhaps use the __mem_to_opcode_arm() helper for the check?
> 
> >>+               if (a32_insn == ARM_INST_UDF)

The following is probably better:

		if (ctx->target[i] == __opcode_to_mem_arm(ARM_INST_UDF))

since then you can take advantage of the compiler optimising the
constant rather than having to do a byte swap on an unknown 32-bit
value.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.