From nobody Fri Dec 19 20:34:46 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1278517B50D; Sun, 24 Mar 2024 23:42:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711323728; cv=none; b=M0rrTVere2km7xoNkLiCYWfr6MZWwFRhD9/UKqEK8nzgRdWcGqyOxKt+kLdW0OW/dmqREqARgi9vucuHcP1+RtdjE992U4Xwk43utLw3mEc3RttM1zQvJMkBt1mbFENPnpsaPt/DY8reUW5wvJUXFekIS6WF6Emc2iX7XdepsbY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711323728; c=relaxed/simple; bh=PdOvL4VS4V6WgvoHtkQ6c36uNe2suX72HRehuZnE9xc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=JbdiCplNd6euXu78qBSCC4cRCInYMEOINq7D3MIc2uXPARPH3sxfUHTRc8oahkkDrecWSiFFBEeEWw7BxBliirKIpKBm5yMbQBR50udn3G6nAzmA98hpGY7IbDWuTRMZIac9gvu8mYhFJrOx6OP+uGRlrCZwnMvy2CvVczI+m0Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=N5E64E31; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="N5E64E31" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50258C433B1; Sun, 24 Mar 2024 23:42:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711323727; bh=PdOvL4VS4V6WgvoHtkQ6c36uNe2suX72HRehuZnE9xc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N5E64E31SVKICn5rmCMk3qlVbOsRa4JppEOcuR7+Hj5VXqqMvrHTi3cl7mXh3Ij7r Z5U75Bh4QP3dITvYnloVnj7zuyccVxwQCBQDBx+ofbU6Pe7SxwwYPVumCvREIQGYBT 2I7hVjFzh8SZgIqW0mHwGTnhftW6vur610t4X3y7Mk0FyNWEi/gY5d8bEzMvChIZBY 1xCrkMfhc0QDxSNeZxTN0fHsywAF51JDolEePN6cnXSNcK9t9Af6jGgCe7DtJj6GuS uxleg9Qs3I+OlNY+S5B8cVNC6BjEoyDmmwWuONMXa3LLhksB8nMj6TQA/og+q8J+E1 zeMceUCBs/MeA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Gustavo A. R. Silva" , "David S . Miller" , Sasha Levin Subject: [PATCH 5.10 101/238] net/ipv4: Replace one-element array with flexible-array member Date: Sun, 24 Mar 2024 19:38:09 -0400 Message-ID: <20240324234027.1354210-102-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240324234027.1354210-1-sashal@kernel.org> References: <20240324234027.1354210-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: quoted-printable From: "Gustavo A. R. Silva" [ Upstream commit 2d3e5caf96b9449af951e63476657acd759c1a30 ] There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use =E2=80=9Cflexible array members=E2=80=9D[1] for these cas= es. The older style of one-element or zero-length arrays should no longer be used[2]. Use an anonymous union with a couple of anonymous structs in order to keep userspace unchanged: $ pahole -C ip_msfilter net/ipv4/ip_sockglue.o struct ip_msfilter { union { struct { __be32 imsf_multiaddr_aux; /* 0 4 */ __be32 imsf_interface_aux; /* 4 4 */ __u32 imsf_fmode_aux; /* 8 4 */ __u32 imsf_numsrc_aux; /* 12 4 */ __be32 imsf_slist[1]; /* 16 4 */ }; /* 0 20 */ struct { __be32 imsf_multiaddr; /* 0 4 */ __be32 imsf_interface; /* 4 4 */ __u32 imsf_fmode; /* 8 4 */ __u32 imsf_numsrc; /* 12 4 */ __be32 imsf_slist_flex[0]; /* 16 0 */ }; /* 0 16 */ }; /* 0 20 */ /* size: 20, cachelines: 1, members: 1 */ /* last cacheline: 20 bytes */ }; Also, refactor the code accordingly and make use of the struct_size() and flex_array_size() helpers. This helps with the ongoing efforts to globally enable -Warray-bounds and get us closer to being able to tighten the FORTIFY_SOURCE routines on memcpy(). [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-leng= th-and-one-element-arrays Link: https://github.com/KSPP/linux/issues/79 Link: https://github.com/KSPP/linux/issues/109 Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller Stable-dep-of: 5c3be3e0eb44 ("ipmr: fix incorrect parameter validation in t= he ip_mroute_getsockopt() function") Signed-off-by: Sasha Levin --- include/uapi/linux/in.h | 21 ++++++++++++++++----- net/ipv4/igmp.c | 12 ++++++------ net/ipv4/ip_sockglue.c | 15 ++++++++------- 3 files changed, 30 insertions(+), 18 deletions(-) diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h index 3960bc3da6b30..066098a5b9360 100644 --- a/include/uapi/linux/in.h +++ b/include/uapi/linux/in.h @@ -190,11 +190,22 @@ struct ip_mreq_source { }; =20 struct ip_msfilter { - __be32 imsf_multiaddr; - __be32 imsf_interface; - __u32 imsf_fmode; - __u32 imsf_numsrc; - __be32 imsf_slist[1]; + union { + struct { + __be32 imsf_multiaddr_aux; + __be32 imsf_interface_aux; + __u32 imsf_fmode_aux; + __u32 imsf_numsrc_aux; + __be32 imsf_slist[1]; + }; + struct { + __be32 imsf_multiaddr; + __be32 imsf_interface; + __u32 imsf_fmode; + __u32 imsf_numsrc; + __be32 imsf_slist_flex[]; + }; + }; }; =20 #define IP_MSFILTER_SIZE(numsrc) \ diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index cb55fede03c04..134f1682a7e9b 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -2493,8 +2493,8 @@ int ip_mc_msfilter(struct sock *sk, struct ip_msfilte= r *msf, int ifindex) goto done; } newpsl->sl_max =3D newpsl->sl_count =3D msf->imsf_numsrc; - memcpy(newpsl->sl_addr, msf->imsf_slist, - msf->imsf_numsrc * sizeof(msf->imsf_slist[0])); + memcpy(newpsl->sl_addr, msf->imsf_slist_flex, + flex_array_size(msf, imsf_slist_flex, msf->imsf_numsrc)); err =3D ip_mc_add_src(in_dev, &msf->imsf_multiaddr, msf->imsf_fmode, newpsl->sl_count, newpsl->sl_addr, 0); if (err) { @@ -2571,14 +2571,14 @@ int ip_mc_msfget(struct sock *sk, struct ip_msfilte= r *msf, count =3D psl->sl_count; } copycount =3D count < msf->imsf_numsrc ? count : msf->imsf_numsrc; - len =3D copycount * sizeof(psl->sl_addr[0]); + len =3D flex_array_size(psl, sl_addr, copycount); msf->imsf_numsrc =3D count; - if (put_user(IP_MSFILTER_SIZE(copycount), optlen) || - copy_to_user(optval, msf, IP_MSFILTER_SIZE(0))) { + if (put_user(struct_size(optval, imsf_slist_flex, copycount), optlen) || + copy_to_user(optval, msf, struct_size(optval, imsf_slist_flex, 0))) { return -EFAULT; } if (len && - copy_to_user(&optval->imsf_slist[0], psl->sl_addr, len)) + copy_to_user(&optval->imsf_slist_flex[0], psl->sl_addr, len)) return -EFAULT; return 0; done: diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 1b35afd326b8d..2cfc507712300 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -670,12 +670,11 @@ static int set_mcast_msfilter(struct sock *sk, int if= index, struct sockaddr_storage *group, struct sockaddr_storage *list) { - int msize =3D IP_MSFILTER_SIZE(numsrc); struct ip_msfilter *msf; struct sockaddr_in *psin; int err, i; =20 - msf =3D kmalloc(msize, GFP_KERNEL); + msf =3D kmalloc(struct_size(msf, imsf_slist_flex, numsrc), GFP_KERNEL); if (!msf) return -ENOBUFS; =20 @@ -691,7 +690,7 @@ static int set_mcast_msfilter(struct sock *sk, int ifin= dex, =20 if (psin->sin_family !=3D AF_INET) goto Eaddrnotavail; - msf->imsf_slist[i] =3D psin->sin_addr.s_addr; + msf->imsf_slist_flex[i] =3D psin->sin_addr.s_addr; } err =3D ip_mc_msfilter(sk, msf, ifindex); kfree(msf); @@ -1236,7 +1235,7 @@ static int do_ip_setsockopt(struct sock *sk, int leve= l, int optname, { struct ip_msfilter *msf; =20 - if (optlen < IP_MSFILTER_SIZE(0)) + if (optlen < struct_size(msf, imsf_slist_flex, 0)) goto e_inval; if (optlen > READ_ONCE(sysctl_optmem_max)) { err =3D -ENOBUFS; @@ -1254,7 +1253,8 @@ static int do_ip_setsockopt(struct sock *sk, int leve= l, int optname, err =3D -ENOBUFS; break; } - if (IP_MSFILTER_SIZE(msf->imsf_numsrc) > optlen) { + if (struct_size(msf, imsf_slist_flex, msf->imsf_numsrc) > + optlen) { kfree(msf); err =3D -EINVAL; break; @@ -1667,11 +1667,12 @@ static int do_ip_getsockopt(struct sock *sk, int le= vel, int optname, { struct ip_msfilter msf; =20 - if (len < IP_MSFILTER_SIZE(0)) { + if (len < struct_size(&msf, imsf_slist_flex, 0)) { err =3D -EINVAL; goto out; } - if (copy_from_user(&msf, optval, IP_MSFILTER_SIZE(0))) { + if (copy_from_user(&msf, optval, + struct_size(&msf, imsf_slist_flex, 0))) { err =3D -EFAULT; goto out; } --=20 2.43.0