From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12EB1C31E4A for ; Thu, 13 Jun 2019 16:20:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFC3B20644 for ; Thu, 13 Jun 2019 16:20:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560442819; bh=ARCRTzY0suUhboJLtjKbJugIFTrD91XgKQg1R1GXuBU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OhX7+WKHtXVNObvt9hHA6gGY8I4f9VnUPxC7H+Io/U/RtMO8LHnApnU0Qk+Wi0WmB 0E5uLEFY0ZBfgYoNeJ5EoDPLwz/ZyrdnU5G9u5e+kmBigNzWqQyuE+mzg0qJev7BF7 JPTwaGgDHaZpbPd5Pu+n5mQpuXh9ZufUVW+zvZVM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392090AbfFMQT5 (ORCPT ); Thu, 13 Jun 2019 12:19:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:57042 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731083AbfFMIjb (ORCPT ); Thu, 13 Jun 2019 04:39:31 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 89D7520851; Thu, 13 Jun 2019 08:39:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560415171; bh=ARCRTzY0suUhboJLtjKbJugIFTrD91XgKQg1R1GXuBU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nmYw9qPO19sSqPZgdLMeuivUL9ZgtAfb8SvaSZKTfUqiP+WBJrxL/tLgiKeI9MlZB flc+08RbwtlWauZr0FS5X7phIKzBsKrT2xbQQ9j++z+DEVFS2wBANkYiWXgOnDn65r i1d332IXidphruD30UHd3s2ZJ69yl4+Jd3+0JQ78= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alban Crequy , =?UTF-8?q?Iago=20L=C3=B3pez=20Galeiras?= , Krzesimir Nowak , Yonghong Song , Daniel Borkmann , Sasha Levin Subject: [PATCH 4.19 028/118] bpf: fix undefined behavior in narrow load handling Date: Thu, 13 Jun 2019 10:32:46 +0200 Message-Id: <20190613075645.165720767@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190613075643.642092651@linuxfoundation.org> References: <20190613075643.642092651@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit e2f7fc0ac6957cabff4cecf6c721979b571af208 ] Commit 31fd85816dbe ("bpf: permits narrower load from bpf program context fields") made the verifier add AND instructions to clear the unwanted bits with a mask when doing a narrow load. The mask is computed with (1 << size * 8) - 1 where "size" is the size of the narrow load. When doing a 4 byte load of a an 8 byte field the verifier shifts the literal 1 by 32 places to the left. This results in an overflow of a signed integer, which is an undefined behavior. Typically, the computed mask was zero, so the result of the narrow load ended up being zero too. Cast the literal to long long to avoid overflows. Note that narrow load of the 4 byte fields does not have the undefined behavior, because the load size can only be either 1 or 2 bytes, so shifting 1 by 8 or 16 places will not overflow it. And reading 4 bytes would not be a narrow load of a 4 bytes field. Fixes: 31fd85816dbe ("bpf: permits narrower load from bpf program context fields") Reviewed-by: Alban Crequy Reviewed-by: Iago López Galeiras Signed-off-by: Krzesimir Nowak Cc: Yonghong Song Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index acc2305ad895..d3580a68dbef 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5743,7 +5743,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) insn->dst_reg, shift); insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, - (1 << size * 8) - 1); + (1ULL << size * 8) - 1); } } -- 2.20.1