From patchwork Fri Jan 28 18:00:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thadeu Lima de Souza Cascardo X-Patchwork-Id: 1585830 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=canonical.com header.i=@canonical.com header.a=rsa-sha256 header.s=20210705 header.b=OlagK7ik; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4Jlldx5Ktnz9t56 for ; Sat, 29 Jan 2022 05:01:57 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1nDVZH-0007UE-5k; Fri, 28 Jan 2022 18:01:51 +0000 Received: from smtp-relay-canonical-0.internal ([10.131.114.83] helo=smtp-relay-canonical-0.canonical.com) by huckleberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1nDVZF-0007Rh-AU for kernel-team@lists.ubuntu.com; Fri, 28 Jan 2022 18:01:49 +0000 Received: from localhost.localdomain (1.general.cascardo.us.vpn [10.172.70.58]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-0.canonical.com (Postfix) with ESMTPSA id A80F040D3E for ; Fri, 28 Jan 2022 18:01:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1643392908; bh=DNGz9udkngAzi4BfcUwpp12IK+Q9/lRg+nkBqnMTqAo=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=OlagK7ikXl5b13ACc634A8fLXtvG3gdwlNmP3vsOqDFfB/fqQxNAT0s0lRRaHcVM9 08eWj5Ofk3vDkXqffcRm5ahyLc2KTsQVBhiDSqTJ/6UnSGF4Rlt6Ki7EzF7Z0rIXZH I7PCIWstx2c1OwYEcdUOzyxrmx3QXuXnVg+Nn1avz4KzP4sVi+PSp0xuwF8uPPe981 HbPrV0zLVdrV/O1zIFVZgFWTxl+nKSXnBuixaSMos16iA3qces9s2xiLvC5dYvbMIZ t7HDbqmX6YXahuh8srAgPI0nQI+EE31ku2gJcZkBjP81TAls+oAGd1Yzr+ioxmJppG JvaxFATzXt8Og== From: Thadeu Lima de Souza Cascardo To: kernel-team@lists.ubuntu.com Subject: [SRU OEM-5.10/HWE-5.11/Impish/OEM-5.14/Jammy 2/3] bpf: Don't promote bogus looking registers after null check. Date: Fri, 28 Jan 2022 15:00:02 -0300 Message-Id: <20220128180003.75186-3-cascardo@canonical.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220128180003.75186-1-cascardo@canonical.com> References: <20220128180003.75186-1-cascardo@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Daniel Borkmann If we ever get to a point again where we convert a bogus looking _or_null typed register containing a non-zero fixed or variable offset, then lets not reset these bounds to zero since they are not and also don't promote the register to a type, but instead leave it as _or_null. Converting to a unknown register could be an avenue as well, but then if we run into this case it would allow to leak a kernel pointer this way. Fixes: f1174f77b50c ("bpf/verifier: rework value tracking") Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov (cherry picked from commit e60b0d12a95dcf16a63225cead4541567f5cb517) CVE-2022-23222 Signed-off-by: Thadeu Lima de Souza Cascardo --- kernel/bpf/verifier.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 296144d71d32..797444bec1aa 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7822,15 +7822,15 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state, { if (reg_type_may_be_null(reg->type) && reg->id == id && !WARN_ON_ONCE(!reg->id)) { - /* Old offset (both fixed and variable parts) should - * have been known-zero, because we don't allow pointer - * arithmetic on pointers that might be NULL. - */ if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || !tnum_equals_const(reg->var_off, 0) || reg->off)) { - __mark_reg_known_zero(reg); - reg->off = 0; + /* Old offset (both fixed and variable parts) should + * have been known-zero, because we don't allow pointer + * arithmetic on pointers that might be NULL. If we + * see this happening, don't convert the register. + */ + return; } if (is_null) { reg->type = SCALAR_VALUE;