From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Mon, 29 Nov 2021 08:16:34 +0100 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by lore.white.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1mratu-0001hR-Mr for lore@lore.pengutronix.de; Mon, 29 Nov 2021 08:16:34 +0100 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mratt-0008Fb-OK for lore@pengutronix.de; Mon, 29 Nov 2021 08:16:34 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=t5mhfAj+Hqznf38d4iV1vdAvdjJ/IlYNvXtW0BDpgtc=; b=uA2GuSzVqp8iGg GlijydXLgz9Q7710Z9ZLvutUDWnPzGXkyxGD0DoHgUg1fllqd3tze0mM68C77RdJAH3d0Vz2PDvDT zEHrXfaH3x3uZDHw9HG0UuniATp7gEgaNkL6gTGbV3Fz1caPono2jqq35C45rHcWEGRwoDheHUZ+O Yvbvwgo+BZCqVKPWhTk3EStGh5Fjhl5ZH5Pzfw+is0Yzh7n+sMMUCVHYgKn+VdTSISAcKphaIewg+ 9Wnsi1d4sRYg7rwn1Y7TqFGRXBcCgLXBhKG6dwF+2a6EVlxlkOEqF6+Wo0RIc76Gikt3Wm4hMBq/q RUHtJ9XJBOd2Rvk0xUXQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mrasW-00Hb6G-Jr; Mon, 29 Nov 2021 07:15:08 +0000 Received: from relay3-d.mail.gandi.net ([217.70.183.195]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mrasR-00Hb48-79 for barebox@lists.infradead.org; Mon, 29 Nov 2021 07:15:04 +0000 Received: (Authenticated sender: ahmad@a3f.at) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id D394C6000C; Mon, 29 Nov 2021 07:14:58 +0000 (UTC) From: Ahmad Fatoum To: barebox@lists.infradead.org Cc: Ahmad Fatoum Date: Mon, 29 Nov 2021 08:14:54 +0100 Message-Id: <20211129071454.2014315-1-ahmad@a3f.at> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211128_231503_431402_6382C27E X-CRM114-Status: UNSURE ( 8.99 ) X-CRM114-Notice: Please train this message. X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:e::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.ext.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.6 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: [PATCH master] fs: /dev/mem: handle copy at offset 0 correctly X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.ext.pengutronix.de) Despite that /dev/mem has a size of 0, the check preventing out-of-bounds access works for /dev/mem as well, because of unsigned wrap around. Corner case is when offset is zero. There will be no wrap around and count = min(count, 0 - 0) = 0 Leading to unexpected behavior with e.g. memcmp -s /dev/mem 0 on systems without MMU. Fix this. Signed-off-by: Ahmad Fatoum --- fs/devfs-core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/devfs-core.c b/fs/devfs-core.c index 3715e543e632..2d016e0e4861 100644 --- a/fs/devfs-core.c +++ b/fs/devfs-core.c @@ -573,7 +573,10 @@ ssize_t mem_copy(struct device_d *dev, void *dst, const void *src, if (!dev || dev->num_resources < 1) return -1; - count = size = min(count, resource_size(&dev->resource[0]) - offset); + if (resource_size(&dev->resource[0]) > 0 || offset != 0) + count = min(count, resource_size(&dev->resource[0]) - offset); + + size = count; /* no rwsize specification given. Do whatever memcpy likes best */ if (!rwsize) { -- 2.33.0 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox