netdev - Re: [PATCH net] bpf, arm: start flushing icache range from header

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: <20151116114055.GC20696@leverpostej>
Date:	Mon, 16 Nov 2015 11:40:55 +0000
From:	Mark Rutland <mark.rutland@....com>
To:	Daniel Borkmann <daniel@...earbox.net>
Cc:	davem@...emloft.net, linux-arm-kernel@...ts.infradead.org,
	netdev@...r.kernel.org, ast@...nel.org, nschichan@...ebox.fr
Subject: Re: [PATCH net] bpf, arm: start flushing icache range from header

On Sat, Nov 14, 2015 at 01:26:53AM +0100, Daniel Borkmann wrote:
> During review I noticed that the icache range we're flushing should
> start at header already and not at ctx.image.
> 
> Reason is that after 55309dd3d4cd ("net: bpf: arm: address randomize
> and write protect JIT code"), we also want to make sure to flush the
> random-sized trap in front of the start of the actual program (analogous
> to x86). No operational differences from user side.
> 
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Tested-by: Nicolas Schichan <nschichan@...ebox.fr>
> Cc: Alexei Starovoitov <ast@...nel.org>
> ---
>  ( As arm32 fixes usually go via Dave's tree, targeting -net. )
> 
>  arch/arm/net/bpf_jit_32.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
> index 2f4b14c..591f9db 100644
> --- a/arch/arm/net/bpf_jit_32.c
> +++ b/arch/arm/net/bpf_jit_32.c
> @@ -1061,7 +1061,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
>  	}
>  	build_epilogue(&ctx);
>  
> -	flush_icache_range((u32)ctx.target, (u32)(ctx.target + ctx.idx));
> +	flush_icache_range((u32)header, (u32)(ctx.target + ctx.idx));

As with the arm64 patch, doesn't this prevent us from flushing the end
of the image? ctx.idx doesn't seem to take into account the header size.

Mark.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html