From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: [PATCH bpf 5/9] bpf: fix missing error return in check_stack_boundary() Date: Mon, 18 Dec 2017 20:11:57 -0800 Message-ID: <20171219041201.1979983-6-ast@kernel.org> References: <20171219041201.1979983-1-ast@kernel.org> Mime-Version: 1.0 Content-Type: text/plain Cc: Daniel Borkmann , Jann Horn , Edward Cree , , To: "David S . Miller" Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:50666 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965492AbdLSEMF (ORCPT ); Mon, 18 Dec 2017 23:12:05 -0500 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vBJ494JK027071 for ; Mon, 18 Dec 2017 20:12:05 -0800 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2exqrvgf3w-6 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Mon, 18 Dec 2017 20:12:05 -0800 In-Reply-To: <20171219041201.1979983-1-ast@kernel.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Jann Horn Prevent indirect stack accesses at non-constant addresses, which would permit reading and corrupting spilled pointers. Fixes: f1174f77b50c ("bpf/verifier: rework value tracking") Signed-off-by: Jann Horn Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ecdc265244ca..77e4b5223867 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1303,6 +1303,7 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno, tnum_strn(tn_buf, sizeof(tn_buf), regs[regno].var_off); verbose(env, "invalid variable stack read R%d var_off=%s\n", regno, tn_buf); + return -EACCES; } off = regs[regno].off + regs[regno].var_off.value; if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || -- 2.9.5