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[81.2.115.148]) by smtp.gmail.com with ESMTPSA id o4sm94588594wrq.66.2019.01.22.10.18.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 22 Jan 2019 10:18:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=BLFuyAs9vbLLhyt9rwFYibPswQ6baGcLx5+zX/if2KE=; b=CkhrtmRek0TXCpoCWqBzz6cY8E5t1FJlZg8poYZrx7a1AjRVuMv4zMClVaC9n+qaSW af4xSyN4zSnDeg5av5NmjeSGS90cSxRX/k7NP1KYdkPcQBynfYQzEEMq3Up8oEUlvyQY 6xDDc+jK24VK/Yj3aFDHUUA5J5xTWkD6/64M8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=BLFuyAs9vbLLhyt9rwFYibPswQ6baGcLx5+zX/if2KE=; b=t/M1+OQiOph6xQUR8kDLy9Hl6EqusD78DQIhNz3U1+KelGumeriAliT4Ihal4PKvjB /3MABkK8RjFFuwbQJfd0x4XGLNd/HK/9++8hUtScJqTZ6vA5njUNVgi2FyCAslbmOjSg uW5EaX93Rc7/B18hCiAG90Ia4YJRXPFFyXw2BqwX/qpTysTQrBv9I3PmtcT6dGzUwDKK ZrVIAS/ji4Grkd06crNM5x82OPmQlwXufzsmQO24AMCMc9j4MYBlEerMjQXN1PvJ9l8O /uhCSnyKKBPSKmW5pblV6fRkkDxeeaHqpqgpa71wNWYi6F8W630ygha28Rw2fdy15Lj5 lBaw== X-Gm-Message-State: AJcUukd8LWvm4QRUWpqvZG60jNO8hAM6mD85LQN151/mHA4bq3MHARAY 55pIU1aIQWRYlX8ZeHWugcCPiXFafFXhbg== X-Google-Smtp-Source: ALg8bN6+X37NkiiHgcaAFEcjjqQEG78mKQ23V0H744G/VWQwrmweBTnpOG0bKVLbV3OyNkrNQ+dGlw== X-Received: by 2002:a5d:4ccb:: with SMTP id c11mr35883142wrt.241.1548181106165; Tue, 22 Jan 2019 10:18:26 -0800 (PST) From: Peter Maydell To: qemu-devel@nongnu.org Date: Tue, 22 Jan 2019 18:18:21 +0000 Message-Id: <20190122181822.1505-2-peter.maydell@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190122181822.1505-1-peter.maydell@linaro.org> References: <20190122181822.1505-1-peter.maydell@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a00:1450:4864:20::442 Subject: [Qemu-devel] [PATCH 1/2] slirp: Avoid marking naturally packed structs as QEMU_PACKED X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Samuel Thibault , Jan Kiszka , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , patches@linaro.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Various ipv6 structs in the slirp headers are marked QEMU_PACKED, but they are actually naturally aligned and will have no padding in them. Instead of marking them with the 'packed' attribute, assert at compile time that they are the size we expect. This allows us to take the address of fields within the structs without risking undefined behaviour, and suppresses clang -Waddress-of-packed-member warnings. Signed-off-by: Peter Maydell Reviewed-by: Eric Blake --- slirp/ip6.h | 12 ++++++++++-- slirp/ip6_icmp.h | 20 +++++++++++++++----- 2 files changed, 25 insertions(+), 7 deletions(-) diff --git a/slirp/ip6.h b/slirp/ip6.h index 14e9c787357..1e3e329ce6a 100644 --- a/slirp/ip6.h +++ b/slirp/ip6.h @@ -133,7 +133,7 @@ struct ip6 { uint8_t ip_nh; /* next header */ uint8_t ip_hl; /* hop limit */ struct in6_addr ip_src, ip_dst; /* source and dest address */ -} QEMU_PACKED; +}; =20 /* * IPv6 pseudo-header used by upper-layer protocols @@ -145,7 +145,15 @@ struct ip6_pseudohdr { uint16_t ih_zero_hi; /* zero */ uint8_t ih_zero_lo; /* zero */ uint8_t ih_nh; /* next header */ -} QEMU_PACKED; +}; =20 +/* + * We don't want to mark these ip6 structs as packed as they are naturally + * correctly aligned; instead assert that there is no stray padding. + * If we marked the struct as packed then we would be unable to take + * the address of any of the fields in it. + */ +QEMU_BUILD_BUG_ON(sizeof(struct ip6) !=3D 40); +QEMU_BUILD_BUG_ON(sizeof(struct ip6_pseudohdr) !=3D 40); =20 #endif diff --git a/slirp/ip6_icmp.h b/slirp/ip6_icmp.h index 32b0914055a..2ad2b75e676 100644 --- a/slirp/ip6_icmp.h +++ b/slirp/ip6_icmp.h @@ -48,12 +48,16 @@ struct ndp_ra { /* Router Advertisement Message */ uint16_t lifetime; /* Router Lifetime */ uint32_t reach_time; /* Reachable Time */ uint32_t retrans_time; /* Retrans Timer */ -} QEMU_PACKED; +}; + +QEMU_BUILD_BUG_ON(sizeof(struct ndp_ra) !=3D 12); =20 struct ndp_ns { /* Neighbor Solicitation Message */ uint32_t reserved; struct in6_addr target; /* Target Address */ -} QEMU_PACKED; +}; + +QEMU_BUILD_BUG_ON(sizeof(struct ndp_ns) !=3D 20); =20 struct ndp_na { /* Neighbor Advertisement Message */ #if G_BYTE_ORDER =3D=3D G_BIG_ENDIAN @@ -72,13 +76,17 @@ struct ndp_na { /* Neighbor Advertisement Message */ reserved_lo:24; #endif struct in6_addr target; /* Target Address */ -} QEMU_PACKED; +}; + +QEMU_BUILD_BUG_ON(sizeof(struct ndp_na) !=3D 20); =20 struct ndp_redirect { uint32_t reserved; struct in6_addr target; /* Target Address */ struct in6_addr dest; /* Destination Address */ -} QEMU_PACKED; +}; + +QEMU_BUILD_BUG_ON(sizeof(struct ndp_redirect) !=3D 36); =20 /* * Structure of an icmpv6 header. @@ -103,7 +111,9 @@ struct icmp6 { #define icmp6_nns icmp6_body.ndp_ns #define icmp6_nna icmp6_body.ndp_na #define icmp6_redirect icmp6_body.ndp_redirect -} QEMU_PACKED; +}; + +QEMU_BUILD_BUG_ON(sizeof(struct icmp6) !=3D 40); =20 #define ICMP6_MINLEN 4 #define ICMP6_ERROR_MINLEN 8 --=20 2.20.1