linux-kernel - Re: [PATCH arm64-next] net: bpf: arm64: fix module memory leak when JIT image build fails

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Message-ID: <20140911104513.GC6158@arm.com>
Date:	Thu, 11 Sep 2014 11:45:13 +0100
From:	Will Deacon <will.deacon@....com>
To:	Daniel Borkmann <dborkman@...hat.com>
Cc:	Catalin Marinas <Catalin.Marinas@....com>,
	Zi Shen Lim <zlim.lnx@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Alexei Starovoitov <ast@...mgrid.com>
Subject: Re: [PATCH arm64-next] net: bpf: arm64: fix module memory leak when
 JIT image build fails

On Thu, Sep 11, 2014 at 10:36:48AM +0100, Daniel Borkmann wrote:
> On ARM64, when the BPF JIT compiler fills the JIT image body with
> opcodes during translation of eBPF into ARM64 opcodes, we may fail
> for several reasons during that phase: one being that we jump to
> the notyet label for not yet supported eBPF instructions such as
> BPF_ST. In that case we only free offsets, but not the actual
> allocated target image where opcodes are being stored. Fix it by
> calling module_free() on dismantle time in case of errors.
> 
> Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
> Cc: Zi Shen Lim <zlim.lnx@...il.com>
> Cc: Alexei Starovoitov <ast@...mgrid.com>
> Cc: Will Deacon <will.deacon@....com>
> ---
>  [ Compile-tested only. ]
> 
>  arch/arm64/net/bpf_jit_comp.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
> index 38c4296..7ae3354 100644
> --- a/arch/arm64/net/bpf_jit_comp.c
> +++ b/arch/arm64/net/bpf_jit_comp.c
> @@ -651,8 +651,10 @@ void bpf_int_jit_compile(struct bpf_prog *prog)
>  	build_prologue(&ctx);
>  
>  	ctx.body_offset = ctx.idx;
> -	if (build_body(&ctx))
> +	if (build_body(&ctx)) {
> +		module_free(NULL, ctx.image);
>  		goto out;
> +	}
>  

Looks good to me:

  Acked-by: Will Deacon <will.deacon@....com>

Catalin, can you apply this on the for-next/core branch, please?

Will
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