From patchwork Tue Oct 22 16:48:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 2000569 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=f13coFq2; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=patchwork.ozlabs.org) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4XXypy6TGNz1xw0 for ; Wed, 23 Oct 2024 03:50:34 +1100 (AEDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t3I4a-0000Hx-B9; Tue, 22 Oct 2024 12:49:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t3I4X-0000GF-IF for qemu-devel@nongnu.org; Tue, 22 Oct 2024 12:49:30 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t3I4R-00064Y-B4 for qemu-devel@nongnu.org; Tue, 22 Oct 2024 12:49:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1729615758; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VDoKVxzboEyOZx7JDyIdlXgX6eUiunNnXmtg/ZwTIlk=; b=f13coFq2pK+lN51b2J3str8kjypkK+h4JwQPM03ZVlDyDh9B6h6f7xuV0drKAvU9asRfQ1 IYLzml8rxhyzrrRegNfSTPulKcbeAg08mdVpDjC2EZhCWISs9bzaPETeKMg25AiF45dN6E gK+t0qpjYzlywBGawCkyKa8dUlo/8js= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-613-jp-gYhGgONWmZrwZfF9gGQ-1; Tue, 22 Oct 2024 12:49:17 -0400 X-MC-Unique: jp-gYhGgONWmZrwZfF9gGQ-1 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A59E7195608C; Tue, 22 Oct 2024 16:49:16 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.39.194.70]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 745541956056; Tue, 22 Oct 2024 16:49:15 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 2/9] block/ssh.c: Don't double-check that characters are hex digits Date: Tue, 22 Oct 2024 18:48:56 +0200 Message-ID: <20241022164903.282174-3-kwolf@redhat.com> In-Reply-To: <20241022164903.282174-1-kwolf@redhat.com> References: <20241022164903.282174-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.519, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1.697, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Peter Maydell In compare_fingerprint() we effectively check whether the characters in the fingerprint are valid hex digits twice: first we do so with qemu_isxdigit(), but then the hex2decimal() function also has a code path where it effectively detects an invalid digit and returns -1. This causes Coverity to complain because it thinks that we might use that -1 value in an expression where it would be an integer overflow. Avoid the double-check of hex digit validity by testing the return values from hex2decimal() rather than doing separate calls to qemu_isxdigit(). Since this means we now use the illegal-character return value from hex2decimal(), rewrite it from "-1" to "UINT_MAX", which has the same effect since the return type is "unsigned" but looks less confusing at the callsites when we detect it with "c0 > 0xf". Resolves: Coverity CID 1547813 Signed-off-by: Peter Maydell Reviewed-by: Kevin Wolf Message-ID: <20241008164708.2966400-3-peter.maydell@linaro.org> Reviewed-by: Richard Henderson Signed-off-by: Kevin Wolf --- block/ssh.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/block/ssh.c b/block/ssh.c index 871e1d4753..9f8140bcb6 100644 --- a/block/ssh.c +++ b/block/ssh.c @@ -364,7 +364,7 @@ static unsigned hex2decimal(char ch) return 10 + (ch - 'A'); } - return -1; + return UINT_MAX; } /* Compare the binary fingerprint (hash of host key) with the @@ -376,13 +376,15 @@ static int compare_fingerprint(const unsigned char *fingerprint, size_t len, unsigned c; while (len > 0) { + unsigned c0, c1; while (*host_key_check == ':') host_key_check++; - if (!qemu_isxdigit(host_key_check[0]) || - !qemu_isxdigit(host_key_check[1])) + c0 = hex2decimal(host_key_check[0]); + c1 = hex2decimal(host_key_check[1]); + if (c0 > 0xf || c1 > 0xf) { return 1; - c = hex2decimal(host_key_check[0]) * 16 + - hex2decimal(host_key_check[1]); + } + c = c0 * 16 + c1; if (c - *fingerprint != 0) return c - *fingerprint; fingerprint++;