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[216.105.38.7]) by mx.google.com with ESMTPS id 46e09a7af769-7189ccd5f81si7927227a34.306.2024.11.06.05.17.32 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Nov 2024 05:17:32 -0800 (PST) Received-SPF: pass (google.com: domain of openvpn-devel-bounces@lists.sourceforge.net designates 216.105.38.7 as permitted sender) client-ip=216.105.38.7; Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@sourceforge.net header.s=x header.b=hkJlcIja; dkim=neutral (body hash did not verify) header.i=@sf.net header.s=x header.b="DOfF5Q/0"; spf=pass (google.com: domain of openvpn-devel-bounces@lists.sourceforge.net designates 216.105.38.7 as permitted sender) smtp.mailfrom=openvpn-devel-bounces@lists.sourceforge.net; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=muc.de Received: from [127.0.0.1] (helo=sfs-ml-4.v29.lw.sourceforge.com) by sfs-ml-4.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1t8fuW-0000oC-1L; Wed, 06 Nov 2024 13:17:24 +0000 Received: from [172.30.29.66] (helo=mx.sourceforge.net) by sfs-ml-4.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1t8fuR-0000o2-6N for openvpn-devel@lists.sourceforge.net; Wed, 06 Nov 2024 13:17:19 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Content-Transfer-Encoding:Content-Type:MIME-Version :References:In-Reply-To:Message-ID:Date:Subject:To:From:Sender:Reply-To:Cc: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=3yj1Re6CXQgxFTieagnlW/PN/dZ/CmCbUr1MgZS5UFI=; b=hkJlcIjafHXl8E3tFcZO0x9aHm vHA5YtzOE6OacGVb9u9Ds4eL2yTEaif6Sow5T2thh27RFECDLRwV5Epn2eviB8eY7NZRMZRcAUFPc Lw6ilgAfOpW4xHoyj2QwaabH1KUYgk3h5YDeMbw3nzzlusce171S9SrZpXI+gQ1kZ45c=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:To:From:Sender:Reply-To:Cc:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=3yj1Re6CXQgxFTieagnlW/PN/dZ/CmCbUr1MgZS5UFI=; b=DOfF5Q/0IFI7eQUdA0KXl6vJDI YQJTJa1hTPjYJq90nLlbkAS9oiPBBB9JKfuMH+dvNoWUxk1HZHIoNfkLcYAccw0KLjzS00qCcyNPa 1ly6kBsrrgVW/Rcihts/k7dmVxtpUptvmXoPg31v30vxhNouuH2ucgE4YDA4OZu8J91E=; Received: from dhcp-174.greenie.muc.de ([193.149.48.174] helo=blue.greenie.muc.de) by sfi-mx-2.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1t8fuP-0007LF-Nv for openvpn-devel@lists.sourceforge.net; Wed, 06 Nov 2024 13:17:19 +0000 Received: from blue.greenie.muc.de (localhost [127.0.0.1]) by blue.greenie.muc.de (8.17.1.9/8.17.1.9) with ESMTP id 4A6DH5pP011079 for ; Wed, 6 Nov 2024 14:17:05 +0100 Received: (from gert@localhost) by blue.greenie.muc.de (8.17.1.9/8.17.1.9/Submit) id 4A6DH5Aq011078 for openvpn-devel@lists.sourceforge.net; Wed, 6 Nov 2024 14:17:05 +0100 From: Gert Doering To: openvpn-devel@lists.sourceforge.net Date: Wed, 6 Nov 2024 14:17:03 +0100 Message-ID: <20241106131705.11069-1-gert@greenie.muc.de> X-Mailer: git-send-email 2.45.2 In-Reply-To: References: MIME-Version: 1.0 X-Spam-Score: -0.0 (/) X-Spam-Report: Spam detection software, running on the system "util-spamd-2.v13.lw.sourceforge.com", has NOT identified this incoming email as spam. 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Content preview: From: Antonio Quartulli The NLMSG_TAIL macro is confusing gcc when compiling with -O3, leading to warnings like: networking_sitnl.c:143:9: warning: writing 4 bytes into a region of size 0 [-Wstringop-overflow=] 143 | memcpy(RTA_DATA(rta), data, alen); | ^ networking_sitnl.c:101:21: note: at offset [72, 88] into [...] Content analysis details: (-0.0 points, 6.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.0 SPF_PASS SPF: sender matches SPF record X-Headers-End: 1t8fuP-0007LF-Nv Subject: [Openvpn-devel] [PATCH v5] sitnl: replace NLMSG_TAIL macro with noinline function X-BeenThere: openvpn-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: openvpn-devel-bounces@lists.sourceforge.net X-getmail-retrieved-from-mailbox: Inbox X-GMAIL-THRID: =?utf-8?q?1814979205602986204?= X-GMAIL-MSGID: =?utf-8?q?1814979205602986204?= From: Antonio Quartulli The NLMSG_TAIL macro is confusing gcc when compiling with -O3, leading to warnings like: networking_sitnl.c:143:9: warning: writing 4 bytes into a region of size 0 [-Wstringop-overflow=] 143 | memcpy(RTA_DATA(rta), data, alen); | ^ networking_sitnl.c:101:21: note: at offset [72, 88] into destination object ‘n’ of size 16 101 | struct nlmsghdr n; | ^ Replacing the macro with a function is also not effective because gcc will inline it and get confused again. The only way out is to write a function that never gets inline'd and replace the macro with it. Tested on linux with gcc and clang. Change-Id: I9306a590a10a7d5cba32abe06d269494fec41ba6 Signed-off-by: Antonio Quartulli Acked-by: Frank Lichtenheld --- This change was reviewed on Gerrit and approved by at least one developer. I request to merge it to master. Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/788 This mail reflects revision 5 of this Change. Acked-by according to Gerrit (reflected above): Frank Lichtenheld diff --git a/src/openvpn/networking_sitnl.c b/src/openvpn/networking_sitnl.c index f53f5ee..6b750e8 100644 --- a/src/openvpn/networking_sitnl.c +++ b/src/openvpn/networking_sitnl.c @@ -52,21 +52,34 @@ } \ } -#define NLMSG_TAIL(nmsg) \ - ((struct rtattr *)(((uint8_t *)(nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len))) - #define SITNL_NEST(_msg, _max_size, _attr) \ ({ \ - struct rtattr *_nest = NLMSG_TAIL(_msg); \ + struct rtattr *_nest = sitnl_nlmsg_tail(_msg); \ SITNL_ADDATTR(_msg, _max_size, _attr, NULL, 0); \ _nest; \ }) -#define SITNL_NEST_END(_msg, _nest) \ - { \ - _nest->rta_len = (void *)NLMSG_TAIL(_msg) - (void *)_nest; \ +#define SITNL_NEST_END(_msg, _nest) \ + { \ + _nest->rta_len = (void *)sitnl_nlmsg_tail(_msg) - (void *)_nest; \ } +/* This function was originally implemented as a macro, but compiling with + * gcc and -O3 was getting confused about the math and thus raising + * security warnings on subsequent memcpy() calls. + * + * Converting the macro to a function was not enough, because gcc was still + * inlining it and falling in the same math trap. + * + * The only way out to avoid any warning/error is to force the function to + * not be inline'd. + */ +static __attribute__ ((noinline)) void * +sitnl_nlmsg_tail(const struct nlmsghdr *nlh) +{ + return (unsigned char *)nlh + NLMSG_ALIGN(nlh->nlmsg_len); +} + /** * Generic address data structure used to pass addresses and prefixes as * argument to AF family agnostic functions @@ -130,7 +143,7 @@ return -EMSGSIZE; } - rta = NLMSG_TAIL(n); + rta = sitnl_nlmsg_tail(n); rta->rta_type = type; rta->rta_len = len;