linux-kernel - Re: [RFC PATCH net-next 2/6] x86: bpf_jit_comp: support BPF_S_ANC_SECCOMP_LD

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Message-ID: <CAKU6vyZfYR-2408G0_Fkp-PS5x5rMH+s4_OOWqqi7Nt+UfiUPg@mail.gmail.com>
Date:	Fri, 26 Apr 2013 10:50:06 -0400
From:	Xi Wang <xi.wang@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Daniel Borkmann <dborkman@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Russell King <linux@....linux.org.uk>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Will Drewry <wad@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH net-next 2/6] x86: bpf_jit_comp: support
 BPF_S_ANC_SECCOMP_LD_W instruction

On Fri, Apr 26, 2013 at 10:18 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Fri, 2013-04-26 at 03:51 -0400, Xi Wang wrote:
>
>> +#ifdef CONFIG_SECCOMP_FILTER
>> +                     case BPF_S_ANC_SECCOMP_LD_W:
>> +                             if (K == offsetof(struct seccomp_data, arch)) {
>> +                                     int arch = syscall_get_arch(current, NULL);
>> +
>> +                                     EMIT1_off32(0xb8, arch); /* mov arch,%eax */
>> +                                     break;
>> +                             }
>> +                             func = (u8 *)seccomp_bpf_load;
>> +                             t_offset = func - (image + addrs[i]);
>> +                             EMIT1_off32(0xbf, K); /* mov imm32,%edi */
>> +                             EMIT1_off32(0xe8, t_offset); /* call seccomp_bpf_load */
>> +                             break;
>> +#endif
>
> This seems seriously wrong to me.

Can you elaborate?

> This cannot have been tested at all.

Thanks to QEMU for hiding bugs then. :)

- xi
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