From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: [PATCH bpf-next] selftests/bpf: make 'dubious pointer arithmetic' test useful Date: Tue, 23 Jan 2018 20:05:51 -0800 Message-ID: <20180124040551.1720570-1-ast@kernel.org> Mime-Version: 1.0 Content-Type: text/plain Cc: , , To: Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:53312 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752094AbeAXEFy (ORCPT ); Tue, 23 Jan 2018 23:05:54 -0500 Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.16.0.22/8.16.0.22) with SMTP id w0O44FNs011481 for ; Tue, 23 Jan 2018 20:05:54 -0800 Received: from mail.thefacebook.com ([199.201.64.23]) by m0089730.ppops.net with ESMTP id 2fpjp9g0p9-4 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Tue, 23 Jan 2018 20:05:54 -0800 Sender: netdev-owner@vger.kernel.org List-ID: mostly revert the previous workaround and make 'dubious pointer arithmetic' test useful again. Use (ptr - ptr) << const instead of ptr << const to generate large scalar. The rest stays as before commit 2b36047e7889. Fixes: 2b36047e7889 ("selftests/bpf: fix test_align") Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/test_align.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/bpf/test_align.c b/tools/testing/selftests/bpf/test_align.c index e19b410125eb..ff8bd7e3e50c 100644 --- a/tools/testing/selftests/bpf/test_align.c +++ b/tools/testing/selftests/bpf/test_align.c @@ -446,11 +446,9 @@ static struct bpf_align_test tests[] = { .insns = { PREP_PKT_POINTERS, BPF_MOV64_IMM(BPF_REG_0, 0), - /* ptr & const => unknown & const */ - BPF_MOV64_REG(BPF_REG_5, BPF_REG_2), - BPF_ALU64_IMM(BPF_AND, BPF_REG_5, 0x40), - /* ptr << const => unknown << const */ - BPF_MOV64_REG(BPF_REG_5, BPF_REG_2), + /* (ptr - ptr) << 2 */ + BPF_MOV64_REG(BPF_REG_5, BPF_REG_3), + BPF_ALU64_REG(BPF_SUB, BPF_REG_5, BPF_REG_2), BPF_ALU64_IMM(BPF_LSH, BPF_REG_5, 2), /* We have a (4n) value. Let's make a packet offset * out of it. First add 14, to make it a (4n+2) @@ -473,8 +471,26 @@ static struct bpf_align_test tests[] = { .prog_type = BPF_PROG_TYPE_SCHED_CLS, .result = REJECT, .matches = { - {4, "R5_w=pkt(id=0,off=0,r=0,imm=0)"}, - /* R5 bitwise operator &= on pointer prohibited */ + {4, "R5_w=pkt_end(id=0,off=0,imm=0)"}, + /* (ptr - ptr) << 2 == unknown, (4n) */ + {6, "R5_w=inv(id=0,smax_value=9223372036854775804,umax_value=18446744073709551612,var_off=(0x0; 0xfffffffffffffffc))"}, + /* (4n) + 14 == (4n+2). We blow our bounds, because + * the add could overflow. + */ + {7, "R5=inv(id=0,var_off=(0x2; 0xfffffffffffffffc))"}, + /* Checked s>=0 */ + {9, "R5=inv(id=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"}, + /* packet pointer + nonnegative (4n+2) */ + {11, "R6_w=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"}, + {13, "R4=pkt(id=1,off=4,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"}, + /* NET_IP_ALIGN + (4n+2) == (4n), alignment is fine. + * We checked the bounds, but it might have been able + * to overflow if the packet pointer started in the + * upper half of the address space. + * So we did not get a 'range' on R6, and the access + * attempt will fail. + */ + {15, "R6=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"}, } }, { -- 2.9.5